Question

90 % of stars plot within the *
○ galaxy
○ known universe
○ main sequence
○ night sky

Explanation:

In stellar astronomy, the Hertzsprung - Russell diagram is used to classify stars. Approximately 90% of stars lie on the main sequence during their stable hydrogen - burning phase. A galaxy is a collection of stars, the known universe is much larger and contains many galaxies, and the night sky is just our view of a small portion of stars. So the correct option is the one related to the main sequence.

Answer:

C. main sequence