Natural polymers are

Options

A. Bakellite
B. Polyisoprene
C. Proteins
D. Polyethylene

Explanation

To determine which of the given options are natural polymers, we will analyze each option based on their origin and composition.

### Step-by-Step Solution:

1. **Understanding Natural Polymers**:
- Natural polymers are substances that occur in nature and are not synthesized artificially. They are typically derived from biological sources.

2. **Analyzing the Options**:
- **Option 1: Bechalite**
- Bechalite is a synthetic polymer made from phenol and formaldehyde. It is used for insulating materials. Therefore, it is not a natural polymer.

- **Option 2: Polyisoprene**
- Polyisoprene is known as natural rubber. It is derived from the sap of rubber trees and is a natural polymer. Thus, this option is correct.

- **Option 3: Protein**
- Proteins are polymers made up of amino acids. They are essential macromolecules found in all living organisms and are considered natural polymers. Therefore, this option is also correct.

- **Option 4: Polyethylene**
- Polyethylene is a synthetic polymer made from the polymerization of ethylene. It is widely used in plastic products and is not a natural polymer.

3. **Conclusion**:
- From the analysis, the correct answers are **Option 2: Polyisoprene** and **Option 3: Protein**, as both are natural polymers.

### Final Answer:
Natural polymers are **Polyisoprene** and **Protein**.

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