An H-R diagram for a globular cluster will show a horizontal branch a line of stars above the main-sequence but to the left of the subgiants and red giants.
Which of the following statements about these horizontal branch stars is true?
a. No correct answer
b. They have inert (non-burning) carbon cores.
c. Their sole source of energy is hydrogen shell burning.
d. They generate energy through both hydrogen fusion and helium fusion. (Correct Answer)
e. In a particular star cluster, all horizontal branch stars have the same spectral type.