Which of the following indicates a byproduct of anaerobic metabolism?

Lactic acid is recognized as a key byproduct of anaerobic metabolism. During anaerobic glycolysis, which is the process that occurs when there is insufficient oxygen for aerobic energy production, glucose is broken down to generate energy. As a result, lactic acid is produced when pyruvate, the end product of glycolysis under anaerobic conditions, is converted to lactic acid.

This process takes place primarily during intense physical activity when oxygen levels are low, leading to an energy production pathway that is less efficient than aerobic metabolism. Lactic acid accumulation in the muscles is often associated with muscle fatigue and discomfort during high-intensity workouts.

Other options like carbon dioxide and oxygen are related to aerobic metabolism; carbon dioxide is a waste product of aerobic respiration, while oxygen is a crucial component required for aerobic processes. Adenosine, while a vital molecule in energy transfer within cells, is not a direct byproduct of anaerobic metabolism itself. Therefore, lactic acid is the most accurate representation of a byproduct from this specific metabolic pathway.