Question

Which of the following statements is true about a light year?

Answer 1

Right answer: It is used to measure long distances in space

A light year ($ly$) is a distance unit that is approximately $9.46×{10}^{12}km$.

By definition it is the distance that a photon would travel in vacuum during a Julian year (365.25 days) at the speed of light (299 792 458 m/s) at an infinite distance from any gravitational field or field magnetic.

In other words:

It is the distance that light can travel in a year.

This unit is used to measure large distances in space. Therefore the correct answer is D.

Answer 2

The answer would be D. This is used to measure long distances in space. An example would be the nearest sun Proxima Centauri is 4.22 light years away.