Answer: Carbon dioxide
Reason: Carbon dioxide is a product of cellular respiration. Cellular respiration is a metabolic process that occurs in cells to produce energy by breaking down glucose and other nutrients. The process involves three main stages: glycolysis, the citric acid cycle (also known as the Krebs cycle or TCA cycle), and oxidative phosphorylation.
During cellular respiration, glucose is broken down, and its chemical energy is converted into adenosine triphosphate (ATP), which is the cell's primary energy currency. Oxygen is consumed in the process as the final electron acceptor in the electron transport chain, and carbon dioxide is produced as a byproduct.