A boy of mass m stands on one end of a wooden plank of length L and mass M. The plank is floating on water. If the boy walks from one end of the plank to the other end at a constant speed, the resulting displacement of the plank is given by :

Options

A. `frac(mL)(M)`
B. `frac(ML)(M)`
C. `frac(mL)(M+m)`
D. `frac(mL)(M-m)`