Let V Be the Volume of the Solid That Lies $y = - \sqrt { 9 - x ^ { 2 } }$

Multiple Choice

Let V be the volume of the solid that lies between planes perpendicular to the x-axis from x = -3 to x = 3. The cross-sections of this solid perpendicular to the x-axis run from $y = - \sqrt { 9 - x ^ { 2 } }$ to $y = \sqrt { 9 - x ^ { 2 } }$ and they are equilateral triangles with bases in the xy-plane. Then V is

A) $18 \sqrt { 2 }$
B) $36 \sqrt { 3 }$
C) 36
D) $18 \sqrt { 5 }$
E) 9