Answer:
Lactic acid.
Explanation:
The glycolysis in muscle cells result in the formation of lactic acid in the muscle. The glycolysis in muscle cells occur anaerobically, in the limited supply of oxygen.
Lactic acid from the muscle cells can enters in the blood. The lactic acid from the blood is taken by the liver and can be converted to pyruvate by the enzyme lactate dehydrogenase.
Thus, the answer is lactic acid.
