Carbon enters atmosphere via combustion in the cycle

Steps:

• Recall the carbon cycle: carbon moves between atmosphere, biosphere, and geosphere through processes like respiration, photosynthesis, and combustion.
• Identify entry to atmosphere: processes releasing CO2 gas, such as burning fossil fuels or organic matter.
• Evaluate options: burning fits release; feeding transfers carbon biologically; fossilisation sequesters it underground; photosynthesis absorbs CO2.
• Confirm: burning oxidizes carbon compounds, producing atmospheric CO2.

Why A is correct:

• Burning (combustion) releases carbon dioxide (CO2) from organic materials or fossil fuels into the atmosphere, as per the reaction C + O2 → CO2.

Why the others are wrong:

• B: Feeding transfers carbon between organisms but does not release it as gas to the atmosphere.
• C: Fossilization stores carbon in sedimentary rocks, removing it from the atmosphere.
• D: Photosynthesis removes CO2 from the atmosphere, incorporating carbon into plant tissues.

Final answer: A