During cellular respiration, when glucose is broken down through glycolysis to produce pyruvic acid, a net total of 2 ATP (not 4, as 2 ATP are used and 4 are produced) are produced along with 2 NADH molecules. Additionally, in aerobic conditions, further processes lead to the production of water and carbon dioxide.
From the options provided, the most relevant product would be water.
So, the correct answer is water.