The respiratory pigment of muscle is called  

Options

A. immunoglobulin
B. thyroglobin
C. 1 & 2
D. myoglobin

Answer

**Step-by-Step Solution:**

1. **Understand the Question**: The question asks for the name of the respiratory pigment found in muscles.

2. **Define Respiratory Pigment**: A respiratory pigment is a molecule that enhances the oxygen-carrying capacity of blood. It plays a crucial role in facilitating cellular respiration by ensuring that oxygen is efficiently transported to tissues.

3. **Identify Examples of Respiratory Pigments**: Hemoglobin is a well-known respiratory pigment found in blood. It is important to differentiate between various proteins that may be confused with respiratory pigments.

4. **Analyze the Options**:
- **Immunoglobulin**: This is an antibody produced by white blood cells that plays a role in the immune response. It does not carry oxygen, so it is incorrect.
- **Thyroglobin**: This is a protein produced by the thyroid gland involved in the synthesis of thyroid hormones. It also does not carry oxygen, making it incorrect.
- **1 and 2**: Since both immunoglobulin and thyroglobin are incorrect, this option is also incorrect.
- **Myoglobin**: This is a cytoplasmic hemoprotein found in skeletal and cardiac muscles. It binds oxygen and increases the rate of oxygen diffusion in muscle fibers, especially during physical activity.

5. **Conclusion**: Based on the analysis, the correct answer is **myoglobin**, as it is the respiratory pigment associated with muscle tissue.

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