Nuclear power plants produce energy using: a. nuclear fission.
b. nuclear fusion.
c. combustion.
d. critical mass.

a. nuclear fission.

Explanation:

Nuclear power plants use heavy materials, like uranium 238, which is bombarded with neutrons. When the neutrons interact with the uranium, there is fission (a division of one atom into smaller ones and other subatomic particles), and in this process, more neutrons are produced. These new neutrons may impact other atoms of uranium and continue with this cycle, generating heat in the process.

Then we can conclude that nuclear power plants produce energy using nuclear fission.

i would think it's food chain