Matching carbon cycle processes to diagram labels

Steps:

• Identify W as the process releasing CO2 from fossil fuels to atmosphere: combustion.
• Identify X as plants absorbing CO2 to form glucose: photosynthesis.
• Identify Z as organisms releasing CO2 back to atmosphere: respiration (noting possible duplicate photosynthesis for another label if present).
• Match to choice listing these in order for W, X, Z.

Why A is correct:

• A aligns with carbon cycle definitions: combustion oxidizes carbon compounds to CO2 (e.g., C + O2 → CO2), photosynthesis fixes CO2 (6CO2 + 6H2O → C6H12O6 + 6O2), and respiration reverses it (C6H12O6 + 6O2 → 6CO2 + 6H2O).

Why the others are wrong:

• B starts with respiration for W, but combustion typically labels fossil fuel release, not biological respiration.
• C repeats B's mismatch, incorrectly assigning respiration to W and Z.
• D assigns respiration to W, ignoring combustion's role in industrial CO2 addition.

Final answer: A