Which of the following is protein of silk ?

Options

A. Myoglobin
B. Keratin
C. Fibroin
D. Haemoglobin

Answer

To answer the question "Which of the following is the protein of silk?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Silk Production**: Silk is produced by certain insects, primarily the silkworm. The silk is a natural fiber made up of proteins.

2. **Identifying the Protein in Silk**: The primary protein that constitutes silk is called fibroin. This protein is secreted by the silkworm during the process of spinning its cocoon.

3. **Examining Other Options**:
- **Hemoglobin**: This is a protein found in red blood cells that carries oxygen. It is not related to silk.
- **Myoglobin**: This protein is found in muscle tissues and helps store oxygen. It is also not related to silk.
- **Keratin**: This protein is found in hair, nails, and the outer layer of skin. It is not the protein found in silk.

4. **Conclusion**: The only protein listed that is associated with silk is fibroin. Therefore, the answer to the question is fibroin.

### Final Answer:
The protein of silk is **fibroin**.

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