Answer;
High temperature and high pressure
Explanation;
- Nuclear fusion is a type of nuclear reaction which involves joining or fusing two or more light nuclei or smaller atoms to form a heavy nuclei or a larger atom.
- Nuclear fusion occurs in presence of high temperatures and high pressure. This is because to bond two nuclei together, they must be thrown together with great force since every nuclei repel each other when they come close.
- The great force required to bring the smaller nuclei together includes both extreme heat and extreme pressure, comparable to that inside stars.