A bullet of mass $$m$$ can penetrate a target, a heavy block of mass $$M$$, up to a distance $$S$$ when the target $$M$$ is held stationary by a stopper $$P$$ shown in figure. Up to what distance $$S'$$ will the bullet penetrate if the block of mass $$M$$ is free to move, that is, when the stopper $$P$$ is removed, on the frictionless surface $$T$$.

A

$$S' = S$$

B

$$S' = \frac{m}{M}S$$

C

$$S' = \frac{m}{m + M}S$$

D

$$S' = \frac{M}{M + m}S$$