Short Answer
3.26 light-years is the best answer.
Astrophysics questions often combine observation with first-principles physics. The winning move is to connect the measurement being made, such as luminosity, spectrum, redshift, or orbit, to the physical model behind it.
1 parsec = 3.0857 × 10¹⁶ m ≈ 3.26 light-years. It's the distance at which 1 AU subtends 1 arcsecond.
Why This Answer Is Correct
This is a Easy-level question in Astrophysics & Cosmology. The prompt is really testing whether you can connect the concept to its defining physical relationship instead of picking a nearby-but-wrong term.
Good astrophysics reasoning always asks what the telescope actually measured and what physical quantity that measurement traces.
Choices At A Glance
- A. 1 light-year
- B. 3.26 light-years
- C. 100 light-years
- D. 1 AU
When similar options appear on an exam, eliminate the ones that break the core law, use the wrong units, or confuse a definition with a consequence.
Topic Snapshot
Topic: Astrophysics & Cosmology
Difficulty: Easy
Best next move: Re-state the governing law in your own words, then solve one more example from the same topic before moving on.