gravitational force magnetic force electric force friction force
I gave my students this multiple choice question: A student wraps a wire around an iron nail. The student then connects the wire to a battery. The nail attracts another nail and they stick together. What force holds the two nails together?

Only one answer is correct among these 4 choices:
- gravitational force
- magnetic force
- electric force
- friction force

Could you tell me which one is correct?

magnetic force