A will become positive w.r.t. B as current induced is in a clockwise direction.
induced current is in anti-clockwise direction when seen from left hand side and its direction is in clockwise when seen from right hand side. Thus, direction of induced current is in clockwise sense.
This implies that plate A of the capacitor is at the higher potential than plate B, i.e. B will be negative plate, while A will be positive plate.
