Which process releases carbon into the atmosphere by burning fossil fuels?

• A. Photosynthesis
• B. Respiration
• C. Combustion
• D. Burial

Answer: (C)

Combustion is the burning of fossil fuels that releases stored carbon as carbon dioxide into the atmosphere. Fossil fuels are hydrocarbons; when they react with oxygen during burning, the carbon combines with oxygen to form CO2 and water, releasing energy as heat. This rapid oxidation puts CO2 directly into the air. By contrast, photosynthesis removes CO2 from the atmosphere as plants convert it into sugars, and burial stores carbon in sediments instead of releasing it. Respiration does release CO2 from living organisms, but not through burning fossil fuels. Since the scenario involves burning fossil fuels, combustion is the process that releases carbon into the atmosphere.