If an Astronaut Were to Look Back from His Spacecraft

Multiple Choice

If an astronaut were to look back from his spacecraft toward the solar system and measure that the angle between Earth and the Sun was 1 arcsecond, how far from the un would the astronaut be? (Assume that the Earth-Sun line is at right angles to your line of sight.)

A) 1 Mpc
B) 1 au
C) 1 pc
D) 1 ly