Short Answer
A cloud of gas and dust in space 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.
A nebula is a giant cloud of gas and dust, often a stellar nursery (emission nebula) or remnant of a dead star (planetary nebula).
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. A type of black hole
- B. A cloud of gas and dust in space
- C. A dead star
- D. A galaxy classification
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.