List-I shows some arrangements in which motion of masses are described and list-II defines motion of centre of mass of the system (m + M). Match appropriate possible options in list-II

Options

A. `{:(,P,Q,R,S),((A),3,1,2,4):}`
B. `{:(,P,Q,R,S),((B),3,2,1,4):}`
C. `{:(,P,Q,R,S),((C),4,2,1,3):}`
D. `{:(,P,Q,R,S),((D),4,1,2,3):}`

Explanation

(P) Since external force in horizontal direction is zero there for COM remains at rest. (Q) If the block remains at rest then centre of mass moves with constant velocity. (R) If m does not slips on M then COM remains at rest otherwise COM is accelerated when m moves from point A to B. (S) The COM is accelerated vertically downwards by the gravity force.