A parachutist is moving down towards the ground with constant speed $v$. The rate at which her gravitational potential energy decreases is $R$. The acceleration of free fall is $g$. What is the mass of the parachutist?
- A$\frac{gv}{R}$
- B$\frac{R}{gv}$
- C$\frac{2R}{v^2}$
- D$\frac{v^2}{2R}$