Nuclear fusion, like the example here, produces huge amounts of energy. Consider the statements below. BUT ONE statement provides more information about nuclear fusion

Explanation:

Nuclear fusion of a form of nuclear reaction in which two small atomic nuclei combines to form larger ones with the release of a large amount of energy.

For example;

                ²₁H  +  ²₁H   →    ⁴₂He  + Energy

The energy released in a nuclear reaction provides the needed temperature for another set of ²H atoms to fuse. This process in turn yields another ⁴He with the release of a lot of energy. Thus, enormous release of energy accompanies a nuclear reaction.

It is based on this principle that an hydrogen bomb is formed.