When you drop a strong magnet through the center of a copper pipe, the magnet(a) descends slowly because its motion causes currents to flow in the pipe and those currents repel the magnet. (b) descends slowly because it is attracted to the magnetic copper metal. (c) descends rapidly because its motion causes currents to flow in the pipe and those currents attract the magnet. (d) falls at the usual rate because copper metal is nonmagnetic.