the Moon to revolve once the Moon to rotate once Earth to rotate once Earth to revolve once
I gave my students this multiple choice question: The length of one day on Earth is determined by how long it takes

Only one answer is correct among these 4 choices:
- the Moon to revolve once
- the Moon to rotate once
- Earth to rotate once
- Earth to revolve once

Could you tell me which one is correct?

Earth to rotate once