Question

Why are very high temperatures and pressures required for fusion to occur?

to generate the neutrons that are needed to break the nuclei
to overcome the repulsion between the protons in the nuclei that join
to maintain the proper conditions to keep the chain reaction going
to keep the uranium fuel separate from the control rods

Answer 1

Explanation:

to overcome the repulsion between the protons in the nuclei that join

Answer 2

Answer:

so as to over come the repulsion between the protons in nuclei that join

Explanation:

it requires high temperature so that the nucleus starts moving at rapid speed which in turn increases their kinetic