Heparin is :-

Options

A. Protein
B. Fat
C. Carbohydrate
D. Mucopolysacchride

Answer

### Step-by-Step Solution:

1. **Understanding Heparin**: Heparin is a substance that plays a crucial role in the body, particularly in the context of blood coagulation.

2. **Classification of Heparin**: Heparin is classified as a mucopolysaccharide. Mucopolysaccharides are long chains of sugar molecules that are important for various biological functions.

3. **Source of Heparin**: Heparin is secreted by mast cells, which are a type of white blood cell involved in the immune response.

4. **Function of Heparin**: The primary function of heparin is to act as a natural anticoagulant. This means it helps to prevent the coagulation (clotting) of blood inside blood vessels, which is essential for maintaining proper blood flow.

5. **Evaluating Options**: The question likely provides multiple-choice options. Based on the information:
- Option A: Protein - Incorrect
- Option B: Fat - Incorrect
- Option C: Carbohydrate - Incorrect
- Option D: Mucopolysaccharide - Correct

6. **Conclusion**: Therefore, the correct answer is that heparin is a mucopolysaccharide.