The initial step in the digestion of milk in humans is carrled by:

Options

A. Rennin
B. Pepsin
C. Lipase
D. Trypsin

Answer

To solve the question regarding the initial step in the digestion of milk in humans, we need to analyze the options provided and understand the role of each enzyme mentioned.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the enzyme responsible for the initial digestion of milk in humans.

2. **Analyzing the Options**:
- **A. Renin**: Renin is a proteolytic enzyme found in the gastric juice of infants. It plays a crucial role in the digestion of milk proteins, particularly casein.
- **B. Pepsin**: Pepsin is another enzyme found in gastric juice, primarily responsible for protein digestion but not specifically for milk.
- **C. Lipase**: Lipase is involved in the digestion of fats, not proteins. It is present in small amounts in gastric juice and mainly in pancreatic juice.
- **D. Trypsin**: Trypsin is an enzyme that digests proteins but is activated in the intestine and does not play a role in the initial digestion of milk.

3. **Identifying the Correct Answer**: Since renin is specifically mentioned as a proteolytic enzyme that aids in the digestion of milk proteins in infants, it is the correct answer.

4. **Conclusion**: The initial step in the digestion of milk in humans is carried out by **A. Renin**.

### Final Answer:
The initial step in the digestion of milk in humans is carried out by **A. Renin**.

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