A Low-Mass Main-Sequence Star's Climb Up the Red Giant Branch

Multiple Choice

A low-mass main-sequence star's climb up the red giant branch is halted by

A) the end of hydrogen shell burning.
B) the beginning of helium fusion in the core.
C) electron-degeneracy pressure in the core.
D) instabilities in the star's expanding outer layers.
E) an explosion that destroys the star.