they have less mass on the moon. their density decreases on the moon. the moon has less gravity than Earth. the moon has less friction than Earth.
I gave my students this multiple choice question: Astronauts weigh more on Earth than they do on the moon because

Only one answer is correct among these 4 choices:
- they have less mass on the moon.
- their density decreases on the moon.
- the moon has less gravity than Earth.
- the moon has less friction than Earth.

Could you tell me which one is correct?

the moon has less gravity than Earth.