Which two energy sources can a star maintain its internal thermal pressure? which two energy sources can a star maintain its internal thermal pressure? nuclear fission and gravitational contraction nuclear fusion and chemical reactions chemical reactions and gravitational contraction nuclear fusion and gravitational contraction nuclear fusion and nuclear fission?

nuclear fission and gravitational contraction

Explanation:

Which two energy sources can help a star maintain its internal thermal pressure? which two energy sources can help a star maintain its internal thermal pressure? nuclear fission and gravitational contraction nuclear fusion and chemical reactions chemical reactions and gravitational contraction nuclear fusion and gravitational contraction nuclear fusion and nuclear fission?

What is Nuclear fission is when a heavy nucleus split to release energy . it splits into two lesser nuclei.

Gravitational contraction:

is when there is collapse of an object in space due to the influence of its own gravity. This two phenomenon makes it possible for a satr to maintain its thermal (heat )pressure.

there are no contact forces mentioned on the list of choices that you've provided.