Medium in which pepsin is active :

Options

A. Neutral
B. Alkaline
C. Acidic
D. Isotonic

Answer

To determine the medium in which pepsin is active, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Pepsin**: Pepsin is a proteolytic enzyme that is responsible for breaking down proteins into smaller peptides. It is secreted in an inactive form called pepsinogen.

2. **Activation of Pepsin**: Pepsinogen is activated to pepsin in the presence of hydrochloric acid (HCl). This activation occurs in the stomach, where the gastric glands secrete HCl.

3. **Identifying the Medium**: Since pepsinogen is converted to pepsin in an acidic environment, we need to identify the pH level of this environment. The pH of gastric juice, which contains HCl, is around 1.8, indicating that it is highly acidic.

4. **Conclusion**: Based on the information that pepsin is activated in the presence of HCl and that this occurs in an acidic medium, we can conclude that the medium in which pepsin is active is acidic.

5. **Final Answer**: The correct option is C - acidic.