the position of the Sun. the position of the Moon. Earth's angle of tilt Earth's distance from the Sun
I gave my students this multiple choice question: The length of time between night and day on Earth varies throughout the year. This time variance is explained primarily by

Only one answer is correct among these 4 choices:
- the position of the Sun.
- the position of the Moon.
- Earth's angle of tilt
- Earth's distance from the Sun

Could you tell me which one is correct?

Earth's angle of tilt