how fast light travels in space. the distance light travels in one year. how large the diameters of different stars are. the time it takes the Sun to move through the galaxy.
I gave my students this multiple choice question: Scientists use the term "light year" to describe

Only one answer is correct among these 4 choices:
- how fast light travels in space.
- the distance light travels in one year.
- how large the diameters of different stars are.
- the time it takes the Sun to move through the galaxy.

Could you tell me which one is correct?

the distance light travels in one year.