Cost price of 100 books is equal to the selling price of 60 books. The gain percentage/loss percentage is

• A. <table><tr><td rowspan="2"> 66</td> <td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3</center></td><td rowspan="2">% </td></tr><td align="center">2</td></table>
• B. 67%
• C. 66%
• D. <table><tr><td rowspan="2"> 66</td> <td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2">% </td></tr><td align="center">3</td></table>