15. Refer to the figure. A conducting loop (square coil of wire) is pulled at constant velocity through a uniform magnetic field entering the plane. Which of the following statements is correct?(A) Current is induced in the loop in the clockwise direction. (B) Current is induced in the loop in the counterclockwise direction. (C) Alternating current is induced in the loop. (D) Charge separation occurs； negative chafes are accumulated at the bottom edge. (E) Charge separation occurs； negative charges are accumulated at the top edge.