Which of the following processes takes place in the carbon cycle?

Step 1: Analyze the question The question asks which process belongs to the carbon cycle, which is the movement of carbon between the atmosphere, living things, soil, and fossil fuels.

Step 2: Explain the concept The carbon cycle involves:

• Photosynthesis: plants take CO₂ from the air to make food.
• Respiration: living things release CO₂.
• Decay/decomposition: microbes break down dead matter and release CO₂.
• Combustion: burning wood, coal, petroleum, and other fuels releases CO₂ into the atmosphere.
• Fossil fuel formation: buried dead organisms become coal and oil, which store carbon.

Step 3: Check each option

• A. Evaporation: part of the water cycle (liquid water turning to vapour). Not the carbon cycle.
• B. Nitrification: part of the nitrogen cycle (bacteria convert ammonium to nitrites and then nitrates). Not the carbon cycle.
• C. Combustion: burning carbon-containing materials releases CO₂ into the air. This is part of the carbon cycle.
• D. Transpiration: loss of water vapour from plant leaves, part of the water cycle.

Step 4: Answer The correct option is C. combustion.

Tip: Match each process to its cycle:

• Carbon cycle: photosynthesis, respiration, decay, combustion
• Nitrogen cycle: nitrification, nitrogen fixation, denitrification
• Water cycle: evaporation, transpiration, condensation, precipitation

If the option mentions burning, think carbon. If it ends in "-ification", think nitrogen. If it involves water vapour, think water cycle.