A ball of mass $$m$$ hits directly another ball of mass $$M$$ at rest and is brought to rest by the impact. One third of the kinetic energy of the ball is lost due to the collision. The coefficient of restitution is

A

$$\frac{1}{3}$$

B

$$\frac{1}{2}$$

C

$$\frac{2}{3}$$

D

$$\sqrt{\frac{2}{3}}$$