In the context of the enzyme chemistry, determine which of the following statements matches the substrate description.

• A. A molecule that increases the rate of the reaction without being changed.
• B. A molecule that binds to the enzyme and is converted into a product.
• C. A molecule that permanently binds to the enzyme, inhibiting its function.
• D. A molecule that serves as a temporary inhibitor that competes with the substrate for the active site.

Answer: (B)