the strength of the gravity the shape of the orbit the size of the planet the length of the day
I gave my students this multiple choice question: All planets of the solar system rotate, but not all planets have the same rotational velocity. Which characteristic of a planet is determined by the rotational velocity of the planet?

Only one answer is correct among these 4 choices:
- the strength of the gravity
- the shape of the orbit
- the size of the planet
- the length of the day

Could you tell me which one is correct?

the length of the day