Question

a person does not experience muscle fatigue and pain when performing normal activities. however, a person experiences these symptoms cause of muscle fatigue and pain during heavy exercise?
the buildup of an acidic compound by the breakdown of glucose anaerobically.
the buildup of an alcoholic compound by the breakdown of glucose anaerobically.
the buildup of water in the muscles due to the quick and complete breakdown of glucose anaerobically.
the buildup of carbon dioxide in the muscles due to the incomplete breakdown of glucose anaerobically.

Explanation:

During heavy exercise, when oxygen supply is limited, glucose undergoes anaerobic breakdown. In humans, this anaerobic breakdown of glucose (glycolysis without sufficient oxygen for further oxidation in the mitochondria) leads to the production of lactic acid (an acidic compound). The buildup of lactic acid in muscles causes fatigue and pain. Alcoholic fermentation (producing an alcoholic compound) occurs in yeast, not in human muscle cells during exercise. The breakdown of glucose anaerobically in humans does not result in a buildup of water in a way that causes these symptoms. Also, incomplete breakdown of glucose anaerobically in humans gives lactic acid, not a significant buildup of carbon dioxide (carbon dioxide is more associated with aerobic respiration and is transported away rather than causing such localized muscle symptoms as described here).

Answer:

The buildup of an acidic compound by the breakdown of glucose anaerobically.