Elastic cartilage is yellowish due to  

Options

A. keratin
B. collagen
C. elastin
D. all the above

Answer

### Step-by-Step Solution:

1. **Understanding the Components of Elastic Cartilage**:
- Elastic cartilage is a type of connective tissue that provides flexibility and support. It is found in structures such as the ear and the epiglottis.

2. **Identifying the Color of Elastic Cartilage**:
- The question asks why elastic cartilage appears yellowish. To answer this, we need to look at the components that contribute to its color.

3. **Analyzing the Options**:
- **Keratin**: This protein is primarily found in hair, skin, and nails. It is associated with a darker color (black or gray) and does not contribute to the yellowish color of elastic cartilage.
- **Collagen**: This is another protein found in connective tissues and is typically white in color. It does not contribute to the yellowish appearance of elastic cartilage.
- **Elastin**: This protein is specifically found in elastic cartilage and is known for its yellowish color. It provides elasticity and flexibility to the cartilage.

4. **Conclusion**:
- Based on the analysis, the yellowish color of elastic cartilage is primarily due to the presence of elastin. Therefore, the correct answer is **elastin**.

5. **Final Answer**:
- Elastic cartilage is yellowish due to **elastin**.