Earth revolves around the sun once per day. The moon revolves around Earth once per day. Earth revolves around the sun once per year. The moon revolves around Earth once per year.
I gave my students this multiple choice question: Which of the following happens in our solar system?

Only one answer is correct among these 4 choices:
- Earth revolves around the sun once per day.
- The moon revolves around Earth once per day.
- Earth revolves around the sun once per year.
- The moon revolves around Earth once per year.

Could you tell me which one is correct?

Earth revolves around the sun once per year.