Which Force Induces the Core to Condense and Collapse in Massive

Multiple Choice

Which force induces the core to condense and collapse in massive stars at the conclusion of each episode of nuclear fusion,such as the carbon,oxygen,and silicon fusion cycles?

A) Gravity
B) The nuclear attractive force between nuclei and between neutrons and protons
C) Gas pressure produced by the very high gas temperatures
D) Electron degeneracy pressure