All stars on the main sequence
A) are at a late stage of evolution after the red-giant stage.
B) are changing slowly in size by gravitational contraction.
C) generate energy by hydrogen fusion in their centers.
D) have approximately the same age to within a few million years.

Question

Quizplus · Accepted Answer

All stars on the main sequence generate energy by hydrogen fusion in their centers. Choices A and B are incorrect as not all stars will go through the red-giant stage and their size is dependent on their mass and evolutionary stage. Choice D is also incorrect as stars on the main sequence can have a wide range of ages depending on their initial mass.

All Stars on the Main Sequence