which of the following binds most tightly to the active site of an enzyme?

The molecule that binds most tightly to the active site of an enzyme is the substrate. The substrate is the specific molecule upon which the enzyme acts, fitting into the enzyme's active site where the chemical reaction takes place. This binding is facilitated by multiple weak interactions such as hydrogen bonding, Van der Waals forces, and electrostatic interactions, which create a complementary fit between the enzyme and substrate, leading to high binding affinity and specificity. The interaction between the substrate and the active site is typically the strongest compared to other molecules since the active site is specially shaped and chemically tailored for that substrate.