In the figure, the block B of mass m starts from rest at the top of a wedge W of mass M. All surfaces are without friction. W can slide on the ground. B slides down onto the ground, moves along it with a speed v, has an elastic collision with the wall, and climbs back two W.

Options

A. B will reach the top of W again
B. From the beginning, till the collision with the wall, the center of mass of 'B plus W' is stationary
C. After the collsion, the center of mass of 'B plus W' moves with a velocity `(2mv)/(m+m)`
D. When B reaches its highest position on W, the speed of W is `(2mv)/(m+M)`