Answer: A.Carbon dioxide
Explanation: Cellular respiration is the process by which glucose molecule breakdown into energy form (ATP) in presence of oxygen. As a result of this reaction ATP is formed and carbon dioxide is released.
Process of cellular respiration completed in following 4 steps :
Glycolysis, Pyruvate Oxidation, Citric acid (Krebs cycle), and Oxidative Phosphorylation.
Reaction of cellular respiration is as follows -
C6H12O6 + 6O2 ------------ 6CO2 +6H2O +38 ATP