Electron affinity of the atom is the energy released when:

Explanation

The correct answer is that electron affinity refers to the energy released when an electron is added to a gaseous atom, resulting in the formation of an anion. This is a key concept in understanding how atoms interact with electrons. Option A is correct because it directly describes this process. Option B is incorrect as it involves breaking bonds, which consumes energy. Option C is incorrect as it describes ionization energy, which is the energy required to remove an electron. Option D is incorrect because forming a covalent bond involves two atoms sharing electrons, which is a different process.