Question

explaining applications of nuclear energy
why are we able to use nuclear energy for practical purposes?
the reactions are controlled to regulate energy output.
the reactions are uncontrolled for maximum energy output.
all of the products are fed back into the reaction to keep it going.
all of the products are immediately removed to inhibit more reactions.

Explanation:

Nuclear energy is used practically when reactions are controlled to regulate energy output. Uncontrolled reactions lead to explosions (like in atomic bombs), not practical energy use. Feeding all products back would be dangerous and unstable, and removing all products would stop the reaction.

Answer:

The reactions are controlled to regulate energy output.