A large wedge rests on a horizontal frictionless surface, as shown. A block starts from rest and slides down the inclined surface of the wedge, which is rough. During the motion of the block, the center of mass of the block and wedge system
[Figure: Block on wedge diagram]
(a) does not move.
(b) moves vertically with increasing speed.
(c) moves horizontally with constant speed.
(d) moves horizontally with increasing speed.
(e) moves both horizontally and vertically.