A competitive inhibitor binds to the enzyme at the

Options

A. Active site
B. Allosteric site
C. To enzyme substrate complex
D. None of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Enzyme Function**: Enzymes are biological catalysts that speed up chemical reactions. They bind to specific molecules called substrates at a region known as the active site.

2. **Defining Competitive Inhibition**: A competitive inhibitor is a substance that resembles the substrate and competes with it for binding to the active site of the enzyme.

3. **Binding of Competitive Inhibitor**: When a competitive inhibitor is present, it can bind to the active site of the enzyme. This prevents the substrate from binding to the active site, thus inhibiting the enzyme's activity.

4. **Impact on Enzyme-Substrate Complex**: Since the competitive inhibitor occupies the active site, the formation of the enzyme-substrate complex is hindered, leading to a decrease in the rate of reaction.

5. **Conclusion**: Therefore, the correct answer to the question is that a competitive inhibitor binds to the enzyme at the **active site**.

---