67.
The answer is: B
Explanation
The correct option is B: nuclear fusion.
A hydrogen bomb, also known as a thermonuclear bomb, is based on the principle of nuclear fusion. In a hydrogen bomb, the nuclei of light elements such as hydrogen isotopes (deuterium and tritium) are forced to combine (or fuse) under extremely high temperatures and pressures. This fusion process releases an enormous amount of energy, significantly more than the energy released in nuclear fission, which is the process used in atomic bombs.
Nuclear fusion is the same process that powers the sun and other stars, where hydrogen nuclei combine to form helium and release vast amounts of energy in the form of light and heat.