The first line of defence is

Options

A. Option1 Antibodies
B. Option2 WBC
C. Option3 Skin
D. Option4 Liver

Answer

To solve the question about the first line of defense in the human body, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Lines of Defense**:
- The immune system has three lines of defense: the first line (non-specific), the second line (non-specific), and the third line (specific).
- The first line of defense is primarily focused on preventing pathogens from entering the body.

2. **Identify the Types of First Line of Defense**:
- The first line of defense can be divided into two categories: physical barriers and chemical barriers.
- Physical barriers include structures that physically block pathogens, while chemical barriers involve substances that can neutralize or destroy pathogens.

3. **Analyze the Options Provided**:
- **Option 1: Antibodies** - These are part of the immune response and are produced in the third line of defense.
- **Option 2: WBC (White Blood Cells)** - These are involved in the second and third lines of defense, responding to infections.
- **Option 3: Skin** - The skin acts as a physical barrier, preventing pathogens from entering the body.
- **Option 4: Liver** - While the liver has important functions in detoxification and metabolism, it is not part of the first line of defense.

4. **Determine the Correct Answer**:
- Based on the analysis, the skin is the primary component of the first line of defense due to its role as a physical barrier against infection.
- Therefore, the correct answer is **Option 3: Skin**.

### Final Answer:
The first line of defense is **Skin** (Option 3).

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