Enzyme pepsin acts upon food at a pH of about `:-`

Options

A. 3 to split proteins
B. 2 to split carbohydrate
C. 7 to change protein into peptones
D. 2 to change protein in amino acids

Answer

### Step-by-Step Solution:

1. **Identify the Enzyme and Its Function**: The enzyme in question is pepsin, which is involved in the digestion of proteins. It breaks down proteins into smaller peptides or amino acids.

2. **Location of Pepsin Secretion**: Pepsin is secreted in the stomach. It is initially secreted in an inactive form known as pepsinogen.

3. **Activation of Pepsin**: Pepsinogen is activated to pepsin in the presence of hydrochloric acid (HCl), which is secreted by the stomach lining.

4. **pH of the Stomach**: The pH of the stomach is very acidic, typically ranging from 1.8 to 2. This low pH is essential for the activation of pepsinogen to pepsin and for the enzyme's activity.

5. **Conclusion**: Since pepsin operates optimally at this acidic pH, the answer to the question is that pepsin acts upon food at a pH of about 2.

### Final Answer:
Pepsin acts upon food at a pH of about **2**.

---