Why might an electromagnet be used to pick up old cars in junk yard?

An electromagnet is a temporary magnet that uses electricity to attract metals. Having this kind of feature makes it easier for junkyard owners to manage used cars through picking and dropping.

Controls on electromagnets are used by trucks, turning electricity off on the electromagnet releases the magnetism which drops the car. Turning on the electricity returns magnetism to the electromagnet.

I believe the best answer is B