Helium Fusion Begins in the Core of a Low-Mass Star

Multiple Choice

Helium fusion begins in the core of a low-mass star after the helium flash. Where did this helium come from?

A) It was part of the original protostar, but before the helium flash, the temperature was not high enough for helium fusion.
B) It was produced by hydrogen fusion during the main-sequence phase.
C) The star acquired it from meteor and comet impacts during the main-sequence phase.
D) It was produced by the helium flash.