The correct option is C radionuclides are released into the atmosphere which spread over long distances by wind.
Nuclear explosion tests are a major cause of radioactive pollution.
During atmospheric nuclear explosion tests, a number of long-lived radionuclides are released into the atmosphere and are then dispersed over long distances by winds from the test site.
These radionuclides often settle down by rain and get mixed with soil and water, easily enter the food chain and finally get deposited in the human body where they cause serious health hazards.