Carbon dioxide is released when which of the following phenomena occur?

Carbon dioxide is added to the atmosphere by human activities. When hydrocarbon fuels ( wood, coal, natural gas, gasoline, and oil) are burned, carbon dioxide is released. During combustion or burning, carbon from fossil fuels combine with oxygen in the air to form carbon dioxide and water vapor.

These natural hydrocarbon fuels come from once-living organisms and are made from carbon and hydrogen, which release carbon dioxide and water when they burn.

Explanation:

So the answer is Fossil Fuels.

the answer to your question is b

b. the carbon cycle ensures living things have a source of hydrogen