What type of radiation involves the emission of particles composed of two protons and two neutrons?

Alpha radiation is characterized by the emission of particles that are composed of two protons and two neutrons. These particles are essentially helium nuclei, and their relatively large mass and positive charge make them distinct from other forms of radiation. When alpha particles are emitted from a radioactive substance, they carry a significant amount of energy, although their ability to penetrate materials is limited, making them less harmful in terms of external exposure but potentially dangerous if ingested or inhaled.

In contrast, beta radiation involves the emission of electrons or positrons, which are much lighter and do not consist of protons and neutrons. X-rays are a form of electromagnetic radiation and do not involve particle emission, while gamma radiation is also a type of electromagnetic radiation emitted from the nucleus of an atom and does not involve the release of particles like protons or neutrons. Therefore, alpha radiation is specifically associated with the emission of these unique particle structures, confirming it as the correct answer.