Let $A = \pi r ^ { 2 }$ If $\frac { d r } { d t } = 1.5$

Let $A = \pi r ^ { 2 }$ If $\frac { d r } { d t } = 1.5$ when then $r = 6,$ is

A) $18 \pi$
B) $16 \pi$
C) $12 \pi$
D) $8 \pi$
E) $4 \pi$