Answer:
A. Enzymes
Explanation:
Metabolic processes that occur in living cells occur with the aid of certain biological catalysts that acts as regulators. These biological catalysts are called ENZYMES. Enzymes are proteinous molecules that control the rate at which certain biochemical reactions occur in living cells.
Breaking down of proteins in cells is an example of metabolic, specifically catabolic, reaction. It occurs with the aid of enzymes called PROTEASES that catalyze the reaction. Protease enzyme helps regulate the breakdown of proteins by binding to them.
