Solve for the Indicated Variable $\mathrm { M } = \pi \mathrm { r } ^ { 2 } \mathrm { hd }$

Multiple Choice

Solve for the indicated variable.
- $\mathrm { M } = \pi \mathrm { r } ^ { 2 } \mathrm { hd }$ , for $\mathrm { r }$

A) $r = \frac { \pm \mathrm { M } \sqrt { \pi h d } } { \pi h d }$
B) $r = \frac { \pm \sqrt { \mathrm { M } \pi \mathrm { hd } } } { \pi \mathrm { hd } }$
C) $r = \frac { \pm \sqrt { \pi \mathrm { Mhd } } } { \mathrm { hd } }$
D) $r = \pm \sqrt { \pi \mathrm { Mhd } }$