Objects in space used for study.?

Question

Which o th efollowing objects would be observed to study properties of stars that have a balance between the forces of gravity and thermal pressure?

A. Red Giant

B. T Tauri Star

C. Protostar

D. Main-Sequence Star

E. White Dwarf

Answer 1

My GUESS is D. I think that's the definition of a Main-Sequence star. Its only when that balance wears out that the star transitions to another state.