the track is waxed the like poles repel the train has a low density a chemical change occurs
I gave my students this multiple choice question: Scientists have created trains that use magnets to make the trains float above the tracks as they travel. These trains float because

Only one answer is correct among these 4 choices:
- the track is waxed
- the like poles repel
- the train has a low density
- a chemical change occurs

Could you tell me which one is correct?

the like poles repel