<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>000160 - Disclosure - 11. Warrants</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

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</LabelSeparator><Level>1</Level><ElementName>us-gaap_DisclosureTextBlockAbstract</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Notes</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>fil_WARRANTS</ElementName><ElementPrefix>fil_</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="D130601_131130" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;!--egx--&gt;&lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;&lt;b&gt;11.&amp;#160; WARRANTS&lt;/b&gt;&lt;/p&gt; &lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;&amp;nbsp;&lt;/p&gt; &lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;There were 7,220,000 warrants outstanding at November 30, 2012, as presented below.&lt;/p&gt; &lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;&amp;nbsp;&lt;/p&gt; &lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;&amp;nbsp;&lt;/p&gt; &lt;table border="0" cellspacing="0" cellpadding="0" style='border-collapse:collapse'&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;Number of warrants&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;Exercise price&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;border:none;border-bottom:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;line-height:normal'&gt;Remaining Life (yrs.)&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;border:none;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;200,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;border:none;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$&amp;#160;&amp;#160; .01&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;border:none;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;3.00&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;240,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$&amp;#160;&amp;#160; .01&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;2.09&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;900,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$&amp;#160;&amp;#160; .05&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;1.93&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;1,160,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$ 1.00&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;&amp;#160; .37&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;1,150,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$ 1.00&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;&amp;#160; .62&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;605,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$ 1.00&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;&amp;#160; .87&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;250,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$&amp;#160;&amp;#160; .25&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;2.00&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; &lt;tr align="left"&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;2,715,000&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;$&amp;#160;&amp;#160; .40&lt;/p&gt; &lt;/td&gt; &lt;td width="144" valign="top" style='width:1.5in;padding:0in 5.4pt 0in 5.4pt'&gt; &lt;p align="center" style='margin-top:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:0in;line-height:115%;margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal'&gt;1.62&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt; 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