Which of the following is NOT a source of radiation?

The choice indicating that radio waves are not a source of radiation is accurate because radio waves are a form of non-ionizing electromagnetic radiation. They fall within the lower frequency range of the electromagnetic spectrum and are primarily used for communication purposes, such as in radio and television broadcasting.

In contrast, gamma rays, X-rays, and neutrons are forms of ionizing radiation, which have enough energy to remove tightly bound electrons from atoms, thus potentially causing damage to biological tissues. Gamma rays and X-rays are both forms of high-energy electromagnetic radiation, while neutrons are subatomic particles that can contribute to radiation exposure, particularly in nuclear reactions. Understanding these distinctions is critical in the context of hazardous waste operations and emergency response, as ionizing radiation poses significant health risks that need to be managed properly.