Solve for the Indicated Variable $$\mathrm { M } = \pi \mathrm { r } ^ { 2 } h \mathrm {~d} , \text { for } \mathrm { r }$$

Solve for the indicated variable. Assume the variable you are solving for must be greater than 0.
- $$\mathrm { M } = \pi \mathrm { r } ^ { 2 } h \mathrm {~d} , \text { for } \mathrm { r }$$

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