Pyruvic acid is the end product of:

Explanation

Pyruvic acid is the end product of glycolysis, the first stage of cellular respiration. During glycolysis, one glucose molecule is enzymatically converted into two molecules of pyruvic acid in the cytoplasm, with a net gain of ATP and NADH. Glycolysis does not involve oxygen and precedes the Krebs cycle and electron transport chain, which occur in the mitochondria. The Krebs cycle processes acetyl-CoA, not pyruvic acid, and the electron transport system produces ATP and water. Oxidation is a broader term referring to electron loss and is not specific to producing pyruvic acid.