Which process contributes significantly to the man-made radiation exposure to humans?

The process of medical imaging significantly contributes to man-made radiation exposure to humans. Medical imaging techniques, such as X-rays and CT scans, utilize ionizing radiation to create detailed images of the inside of the body. This use of radiation is for diagnostic purposes, helping healthcare providers identify and treat medical conditions.

The exposure from these imaging procedures can accumulate, especially as individuals may undergo multiple scans over a lifetime. Thus, the cumulative effect from medical imaging can lead to a notable increase in overall radiation exposure compared to other man-made sources.

While nuclear weapons testing, nuclear energy production, and burning fossil fuels have associated radiation risks, they do not contribute to individual radiation exposure to the same extent as medical imaging does. Nuclear weapons testing has been largely restricted since the late 20th century, and the radiation from nuclear power plants is generally well-contained and regulated. Burning fossil fuels can lead to environmental pollution but does not directly expose individuals to significant radiation levels.

Therefore, medical imaging stands out as a key contributor to man-made radiation exposure among the options provided.