The Formation of a Star Requires the Consideration of the Effects

The formation of a star requires the consideration of the effects of gravity and the energy from nuclear reactions and a star will form only when both the temperature and density are sufficiently high.In the birth of a star:

A) gravity produces the initial required high temperature and density.
B) nuclear reactions produce the initial high temperature.
C) nuclear reactions produce the initial required high density.
D) nuclear reactions produce the initial required high temperature and density.