63. During a metabolic pathway, the accumulation of a specific intermediate inhibits the activity of the pathway's first enzyme. This type of regulation is known as: (A) Competitive inhibition, where the intermediate competes with the substrate for the active site. (B) Non-competitive inhibition, where the intermediate binds to a different site on the enzyme. (C) Feedback inhibition, where the intermediate acts as a regulator of the pathway. (D) Allosteric activation, where the intermediate enhances the enzyme's activity.