What is the process of radioactivity?

Radioactivity refers to the phenomenon where unstable atomic nuclei undergo a spontaneous transformation to achieve stability, which often involves the emission of radiation. This process typically occurs when an atomic nucleus is unstable due to an imbalance in the number of protons and neutrons.

When a nucleus decays, it may emit various forms of radiation, including alpha particles, beta particles, or gamma rays. This emission allows the nucleus to move towards a more stable configuration. The term "spontaneous" highlights that this process occurs without external influence, and it is intrinsic to the nature of certain isotopes.

In contrast, the other options do not accurately capture the full scope of what radioactivity entails. Stabilizing atoms or generating energy describes characteristics related to broader nuclear processes but does not specifically define the act of radioactivity. The emission of electrons, while part of beta decay, is not the sole aspect of radioactivity, as it involves different types of particles and radiation. Thus, the defining statement of radioactivity as the spontaneous breakdown of unstable nuclei with the corresponding emission of radiation aligns perfectly with the selected answer.