Which of the following best describes the majority source of radiation exposure for most people?

Natural sources of radiation exposure are indeed the predominant contributor for most individuals. This includes a variety of environmental sources, such as cosmic rays from outer space, terrestrial radiation from radioactive materials in the earth (such as uranium and radon), and even radiation from our own bodies. Natural background radiation accounts for approximately 80% of the exposure that an average person receives, making it the largest source of radiation in daily life.

In contrast, while medical procedures can contribute significantly to an individual's radiation dose, they are generally not as widespread across the population as natural sources. Cosmic and industrial sources also provide relatively minor contributions to overall radiation exposure when compared to natural sources. Thus, when considering the majority source of radiation exposure for most people, natural sources clearly dominate.