the period of rotation of the Moon around its axis the period of revolution of the Moon around Earth the period of rotation of Earth around its axis the period of revolution of Earth around the Sun
I gave my students this multiple choice question: What determines how long the Moon takes to complete one cycle of phases?

Only one answer is correct among these 4 choices:
- the period of rotation of the Moon around its axis
- the period of revolution of the Moon around Earth
- the period of rotation of Earth around its axis
- the period of revolution of Earth around the Sun

Could you tell me which one is correct?

the period of revolution of the Moon around Earth