Final answer:
Pyruvate dehydrogenase is inhibited by its products, NADH and acetyl CoA, as well as by ATP which signals high energy. However, CO2 is a product, not a regulator, and AMP does not directly regulate this enzyme, making 'C) AMP' the correct answer to the question.
Step-by-step explanation:
The enzyme pyruvate dehydrogenase is regulated by a number of factors within the cell. These regulatory factors include NADH, which is a product of the enzyme's activity, and acetyl CoA, the product of pyruvate's decarboxylation by the enzyme. Both NADH and acetyl CoA serve to inhibit the enzyme's activity when they are abundant, indicating that the cell does not require further energy production from glucose breakdown at that time. Another regulator is ATP, which acts as a signal of energy sufficiency; high levels of ATP inhibit the enzyme's activity. However, CO2 (carbon dioxide) is not a known regulator of pyruvate dehydrogenase. Instead, CO2 is actually a product of the reaction catalyzed by pyruvate dehydrogenase.