The base of a right circular cone has the same radius a as that of a sphere. Both the sphere and the cone have the same volume. Height of the cone is

• A. 3a
• B. 4a
• C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>7</center></td><td rowspan="2">a</td></tr><tr><td style="text-align: center;">4</td></tr></table>
• D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>7</center></td><td rowspan="2">a</td></tr><tr><td style="text-align: center;">3</td></tr></table>