Final answer:
The decay of radium-226 resulting in radon-222 and an alpha particle is an example of alpha decay. Option a.
Step-by-step explanation:
The type of radioactive decay described by the equation 88Ra 226 → ZRn A + 2He is alpha decay. This process involves a radium-226 nucleus undergoing decay to form radon-222 and an alpha particle, which is identical to a helium nucleus (two protons and two neutrons). In alpha decay, the atomic number decreases by two and the mass number decreases by four. This is consistent with the decay of radium-226 since it transforms into an atom with an atomic number two less (radon with atomic number 86) and a mass number four less, thus the correct answer to the question is A. Alpha decay.