First line of defence of body is

Options

A. Skin and Mucous Membrane
B. Neutrophils and monocytes
C. Fever
D. interferon

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the first line of defense in the human body against pathogens.

2. **Identifying the Lines of Defense**: The immune system has multiple lines of defense. The first line consists of physical and physiological barriers.

3. **Physical Barriers**: The primary physical barriers include:
- **Skin**: Acts as a protective layer covering the body and preventing the entry of pathogens.
- **Mucous Membranes**: These membranes line various tracts in the body (such as respiratory and gastrointestinal tracts) and help trap pathogens.

4. **Physiological Barriers**: In addition to physical barriers, physiological barriers also play a role. These include:
- **Fever**: A physiological response that can inhibit the growth of pathogens.
- **Interferons**: Proteins that help protect cells from viral infections.

5. **Conclusion**: The first line of defense primarily consists of the skin and mucous membranes, which are physical barriers that prevent the entry of microorganisms into the body.

6. **Final Answer**: Therefore, the first line of defense of the body is the **skin and mucous membranes**.

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