Find the Volume of the Described Solid $y = 3 \cos x$

Find the volume of the described solid.
-The base of a solid is the region between the curve $y = 3 \cos x$ and the $x$ -axis from $x = 0$ to $x = \pi / 2$ . The cross sections perpendicular to the $x$ -axis are squares with bases running from the $x$ -axis to the curve.

A) $2 \pi$
B) $\frac { 3 } { 2 } \pi$
C) $\frac { 9 } { 2 } \pi$
D) $\frac { 9 } { 4 } \pi$