What type of radiation is characterized by having mass?

Particulate radiation is characterized by having mass because it consists of particles that have tangible mass and can be ascribed physical properties such as momentum and energy. This type of radiation includes alpha particles, beta particles, and neutrons, all of which are composed of actual material and can interact with matter in a direct way, contributing to their ability to ionize atoms.

In contrast, electromagnetic radiation includes forms like X-rays and gamma rays, which have no mass and consist of energy that travels in waves. Microwave and optical radiation also fall under the umbrella of electromagnetic radiation and share this characteristic of being massless. Thus, when distinguishing types of radiation based on the presence of mass, particulate radiation stands out as the correct choice.