A coil is wrapped loosely around a cylindrical wooden piece and its ends are connected to a battery as shown. In which case will the compass needle placed near the coil deflect when the circuit is closed? A. Only if the cylindrical wooden piece is replaced by an iron piece. B. Only if the cylindrical wooden piece is replaced by a magnet. C. Only if the cylindrical wooden piece is replaced by a magnet which is moved in and out of the coil. D. The needle will deflect even with the wooden piece alone.
