What "Safety Valve" Operates in the Gas of Normal (Nondegenerate)stars

Multiple Choice

What "safety valve" operates in the gas of normal (nondegenerate) stars?

A) If the star gets too big,it will collapse into a black hole.
B) If the stellar gas is suddenly heated,it will expand and cool.
C) If the pressure gets too high,electrons will combine with protons to relieve the pressure.
D) If thermonuclear reactions proceed too quickly,the star will run out of fuel before anything drastic happens.