In aerobic respiration, carbohydrates are ultimately broken down into which gas?

In aerobic respiration, carbohydrates undergo a series of chemical reactions where they are oxidized to release energy. The final products of this metabolic process include carbon dioxide and water, among others. Specifically, during the complete oxidation of glucose (a common carbohydrate) in the presence of oxygen, carbon dioxide is produced as a byproduct.

This carbon dioxide is formed during several stages of aerobic respiration, notably during the citric acid cycle (Krebs cycle) and is then expelled from the organism as a waste product. The oxygen, which is essential for aerobic respiration, is consumed in the process rather than produced. The production of hydrogen or methane does not occur in standard aerobic respiration of carbohydrates. Thus, the gas ultimately produced is carbon dioxide, making it the correct answer to the question.