visiting the Moon a stone eroding in a river living on the space station a ship floating on the ocean
I gave my students this multiple choice question: The meanings of mass and weight can often be confused. Which is an example of a change in both mass and weight?

Only one answer is correct among these 4 choices:
- visiting the Moon
- a stone eroding in a river
- living on the space station
- a ship floating on the ocean

Could you tell me which one is correct?

a stone eroding in a river