AP BIOLOGY

Detailed explanation-1: -So, the correct answer is ‘Photosynthesis’.

Detailed explanation-2: -Any process that uses fossil fuels-such as burning coal to make electricity-releases a lot of carbon into the atmosphere. Raising cattle for food also releases a lot of carbon into the atmosphere. These processes that release carbon into the atmosphere are known as carbon sources.

Detailed explanation-3: -Photosynthesis removes CO2 from the atmosphere and replaces it with O2. Respiration takes O2 from the atmosphere and replaces it with CO2.

Detailed explanation-4: -Carbon dioxide is added to the atmosphere naturally when organisms respire or decompose (decay), carbonate rocks are weathered, forest fires occur, and volcanoes erupt. Carbon dioxide is also added to the atmosphere through human activities, such as the burning of fossil fuels and forests and the production of cement.