AB and CD are fixed conducting smooth rails placed in a vertical plane and joined by a constant current source at its upper end. PQ is a conducting rod which is free to slide on the rails. A horizontal uniform magnetic field exists in space as shown. If the rod PQ is released from rest then,
(A) The rod PQ may move downward with constant acceleration
(B) The rod PQ may move upward with constant acceleration
(C) The rod will move downward with decreasing acceleration and finally aquire a constant velocity
(D) either A or B.
