Answer:
C. ultraviolet radiation.
Step-by-step explanation:
Cell injury occurs when cells undergo specific changes when subjected to an internal factor or an external factor. Such change causes "illness" to the person.
Under "toxic injury," two sources may cause an injury to the cell. These are endogenous and exogenous factors. Endogenous factors originate within the body while the exogenous factors originate from the environment.
Among the choices above, it is only the ultraviolet radiation that is considered an exogenous factor because it originates from outside the person's body. Prolonged exposure to UV light damages the cells which can lead to cancer.