Cocoon is made of protein

Options

A. Myosin
B. Fibroin
C. Tubulin
D. Sericin.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question states that "Cocoon is made of protein." We need to identify which protein is primarily responsible for the structure of the cocoon.

2. **Analyzing the Options**:
- **Option A: Myosin** - Myosin is a protein that is primarily found in muscle tissues, specifically in skeletal muscles. It is not related to the structure of a cocoon. Therefore, this option is incorrect.

- **Option B: Fibrin** - Fibrin is a protein involved in blood clotting, but it is not the main component of a cocoon. This option is also incorrect.

- **Option C: Fibroin** - Fibroin is a protein that is a major component of silk produced by silkworms. It is the primary protein found in the cocoon. This option is correct.

- **Option D: Tubulin** - Tubulin is a protein that forms microtubules in the cytoskeleton of cells. It is not related to the cocoon structure, making this option incorrect.

- **Option E: Sericin** - Sericin is a protein that coats the fibroin in silk but is not the main structural protein of the cocoon itself. Therefore, this option is also incorrect.

3. **Conclusion**: After analyzing all the options, the correct answer is **Option C: Fibroin**, as it is the principal protein that makes up the cocoon.

### Final Answer:
The cocoon is primarily made of the protein **Fibroin**.

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