What is the process called in which multiple atomic nuclei are combined to form a larger one?

The process in which multiple atomic nuclei combine to form a larger nucleus is called nuclear fusion. This phenomenon occurs naturally in stars, including our sun, where hydrogen nuclei fuse together under immense pressure and temperature to create helium, releasing a vast amount of energy in the process. Fusion is characterized by the uniting of light nuclei, resulting in a heavier nucleus and a release of energy that can be harnessed for various applications, including potential energy generation on Earth.

In contrast, nuclear fission refers to the splitting of a large atomic nucleus into smaller nuclei, which releases energy as well but is fundamentally different from fusion. Radioactive decay involves the transformation of an unstable atomic nucleus into a more stable one, which may involve emission of particles or electromagnetic radiation. Alpha decay is a specific type of radioactive decay where an alpha particle (two protons and two neutrons) is emitted from the nucleus. Therefore, the process of combining nuclei specifically points to nuclear fusion as the correct answer.