Common polysaccharide found in ground substance of connective tissue include :

Options

A. Hyaluronic acid
B. Melatonin
C. Cholesterol
D. All of the above

Answer

To answer the question regarding the common polysaccharide found in the ground substance of connective tissue, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for common polysaccharides found in the ground substance of connective tissue. We need to identify which of the given options fits this description.

2. **Analyzing the Options**:
- **Option A: Hyaluronic Acid**: This is a polysaccharide that is indeed found in the ground substance of connective tissue. It is produced by fibroblast cells and plays a crucial role in retaining water, which helps maintain the hydration and elasticity of the tissue.
- **Option B: Melatonin**: This is a hormone secreted by the pineal gland, primarily involved in regulating sleep cycles and is not a polysaccharide. Therefore, it is not relevant to the question.
- **Option C: Cholesterol**: Cholesterol is a lipid found in cell membranes, not a polysaccharide, and thus does not belong in the context of ground substance in connective tissue.
- **Option D: All of the Above**: Since both melatonin and cholesterol are not polysaccharides found in connective tissue, this option is incorrect.

3. **Conclusion**: Based on the analysis, the only correct answer is **Hyaluronic Acid** as it is a common polysaccharide found in the ground substance of connective tissue.

### Final Answer:
The common polysaccharide found in the ground substance of connective tissue is **Hyaluronic Acid**.