Chaperonins are

Options

A. Antifreeze proteins
B. Heat shock proteins
C. Transport proteins
D. Osmotic proteins

Answer

### Step-by-Step Solution:

1. **Understanding Chaperonins**: Chaperonins are a specific type of protein that assist in the proper folding of other proteins. They are crucial for ensuring that proteins achieve their functional three-dimensional structures.

2. **Identifying the Options**: The question provides four options:
- Antifreeze proteins
- Heat shock proteins
- Transport proteins
- Osmotic proteins

3. **Analyzing Each Option**:
- **Antifreeze Proteins**: These proteins help organisms survive in freezing temperatures by preventing ice crystal formation. They do not assist in protein folding.
- **Heat Shock Proteins**: These are a family of proteins produced in response to stress (like heat). They help in the correct folding of other proteins and prevent aggregation, making them a type of chaperonin.
- **Transport Proteins**: These proteins are responsible for the movement of substances across cell membranes. They do not play a role in protein folding.
- **Osmotic Proteins**: These proteins are involved in osmosis and the regulation of water movement in cells. They are not related to protein folding.

4. **Choosing the Correct Answer**: Based on the analysis, the correct answer is **Heat Shock Proteins**, as they are indeed a type of chaperonin that assist in the proper folding of proteins under stressful conditions.

5. **Conclusion**: Therefore, the correct option for the question "Chaperonins are" is **Heat Shock Proteins**.