Why does the apparent Km increase in the presence of a competitive inhibitor?

• A. Because the inhibitor binds to the enzyme-substrate complex, increasing substrate binding.
• B. Because the inhibitor decreases the enzyme's affinity for the substrate.
• C. Because the inhibitor increases the enzyme's affinity for the substrate.
• D. Because the inhibitor competes with the substrate for the active site, reducing substrate binding.

Answer: (D)