What feature is common among these three --- amylase, rennin and trypsin?

Options

A. These are all proteins
B. The are proteolytic enzymes
C. These are produced in stomach
D. These act at a pH lower than 7

Explanation

To determine the common feature among amylase, rennin, and trypsin, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Nature of the Enzymes**:
- Amylase is an enzyme that digests carbohydrates.
- Rennin is an enzyme that digests milk proteins, especially in infants.
- Trypsin is an enzyme that digests proteins and is secreted in an inactive form (trypsinogen) by the pancreas.

2. **Classify the Enzymes**:
- All three enzymes (amylase, rennin, and trypsin) are classified as enzymes, which are biological catalysts that speed up chemical reactions in the body.

3. **Determine the Composition of Enzymes**:
- Enzymes are primarily proteins. This means that all three enzymes mentioned are proteins.

4. **Conclusion**:
- The common feature among amylase, rennin, and trypsin is that they are all proteins.

### Final Answer:
The common feature among amylase, rennin, and trypsin is that they are all enzymes and are composed of proteins.