Why is the rate of reaction of an enzyme-catalyzed reaction proportional to the amount of ES complex?

A. The ES complex represents the activated state of the enzyme, leading to a higher likelihood of product formation.
B. The ES complex stabilizes the substrate, facilitating the conversion to the product.
C. The ES complex enhances the binding affinity between the enzyme and substrate, promoting efficient catalysis.
D. The ES complex serves as a reservoir for substrate molecules, ensuring a continuous supply for the reaction.