Thin fibres which form network in connective tissue are made up of  

Options

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

Answer

To solve the question "Thin fibres which form network in connective tissue are made up of," we will analyze the options provided and identify the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding Connective Tissue**:
- Connective tissue is a type of tissue that supports, binds together, and protects tissues and organs of the body. It consists of cells scattered within an extracellular matrix that includes fibers and ground substance.

2. **Identifying the Fibers in Connective Tissue**:
- The question specifically asks about thin fibers that form networks in connective tissue. These fibers play a crucial role in providing structural support.

3. **Analyzing the Options**:
- The options given are:
- A) Elastin
- B) Collagen
- C) Fibrin
- D) All of the above

4. **Evaluating Each Option**:
- **Elastin**: This is a protein that provides elasticity to tissues. While it is present in connective tissue, it is not the primary fiber that forms the network.
- **Collagen**: This is the main structural protein in connective tissue. It is the most abundant protein in mammals and forms a network of fibers that provide strength and support to tissues.
- **Fibrin**: This is a protein involved in blood clotting and is not primarily associated with the structural network of connective tissue.
- **All of the above**: Since elastin and fibrin do not primarily form the network in connective tissue, this option can be eliminated.

5. **Conclusion**:
- The correct answer is **B) Collagen**, as it is the main structural protein that forms the thin fibers creating a network in connective tissue.

### Final Answer:
**B) Collagen**