diameter of the planet rotational speed of the planet speed of a planet in orbit around the sun diameter of the orbit of a planet around the sun
I gave my students this multiple choice question: One solar day on Jupiter lasts only 9 hours and 50 minutes. What causes a solar day?

Only one answer is correct among these 4 choices:
- diameter of the planet
- rotational speed of the planet
- speed of a planet in orbit around the sun
- diameter of the orbit of a planet around the sun

Could you tell me which one is correct?

rotational speed of the planet