Arsenic contamination of groundwater in the U. S., China, and many other countries comes from: A. agricultural runoff. B. municipal wastewater. C. natural sources. D. nuclear power plants. E. septic systems.

D. nuclear power plants.

Explanation:

Arsenic pollution of groundwater is a form of groundwater contamination, which naturally occurs in high concentrations of arsenic in deep groundwater. Nuclear power plants provide 17% of the world’s electricity. There are over 400 nuclear power plants worldwide And the production of solar elements and cumulative use gallium, arsenic, selenium and other elements, which become heavy pollutants as they disposal in ground.

I'm pretty sure it's c. extremely gradual but not 100% sure though.

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