An astronomer observes an asteroid in the solar system. He notes that the asteroid is three times farther from the Sun than Earth is.How far away from the Sun is the asteroid in astronomical units?

Earth is 1 astronomical unit (AU) from the Sun. The asteroid is three times as far away, so its distance is 3 × 1 AU = 3 AU. Therefore, the correct choice is 3 AU.

AI-written and checked against the verified answer.