The correct answer is A. Nearly equal masses with a release of energy and radiation.

However, nuclear fusion actually involves the combining of two light nuclei to form a heavier nucleus, not the splitting of a heavy element. This process releases a significant amount of energy and, in some cases, radiation.

Examples of nuclear fusion include:

- The sun's core, where hydrogen nuclei (protons) fuse to form helium, releasing vast amounts of energy in the process.

- Fusion reactions in tokamaks and other experimental devices, where isotopes of hydrogen (such as deuterium and tritium) are fused to form helium and release energy.

The correct description of nuclear fission, on the other hand, is:

- The splitting of a heavy element (such as uranium or plutonium) into two or more lighter nuclei, releasing energy and radiation in the process.