What happens during nuclear fusion?

During nuclear fusion, two light atomic nuclei combine to form a heavier nucleus. This process involves immense pressure and temperature, typically found in stars, allowing hydrogen nuclei to fuse into helium and release a significant amount of energy in the process. This energy is what powers stars, including our sun, and is responsible for the heat and light they produce.

The fusion process is fundamental to understanding stellar development and energy production, as opposed to other nuclear reactions like fission, which involves the splitting of heavy nuclei into lighter ones. The alternatives presented do not accurately represent fusion; they describe different types of nuclear reactions. For instance, splitting heavy elements into lighter ones refers to nuclear fission, which is not representative of what occurs during fusion. Similarly, bombarding atomic nuclei with neutrons or adding electrons to light nuclei does not align with the fusion process, which is strictly about the combination of light elements to form heavier ones. Thus, the correct understanding of nuclear fusion is highlighted by the combination of light nuclei into a heavier nucleus.