What is nuclear fusion and how does it relate to energy release?

Nuclear fusion is the process in which two light nuclei combine to form a heavier nucleus. This process releases a significant amount of energy, primarily because the mass of the resulting nucleus is less than the sum of the masses of the original nuclei, with the missing mass converted into energy according to Einstein's equation E=mc².

This question tests the understanding of the concept of nuclear fusion and its energy implications. It requires students to recall the definition of fusion and explain the energy release mechanism, demonstrating their grasp of fundamental nuclear physics.