Which is wrong regarding lines of defence?

Options

A. body's first line of defence is skin
B. Second line of defence is skin and phagocytic cells
C. Third line of defence is immune system
D. Lines of body defence are skin, phagocytic cells and immune system.

Answer

### Step-by-Step Solution:

1. **Understanding the Lines of Defense**:
- The human body has three lines of defense against pathogens.
- The first line consists of physical and physiological barriers.
- The second line involves cellular responses and immune mechanisms.
- The third line is related to acquired immunity.

2. **Identifying the First Line of Defense**:
- The first line of defense includes the skin and mucous membranes which act as barriers to prevent pathogen entry.

3. **Identifying the Second Line of Defense**:
- The second line of defense includes phagocytic cells (like macrophages and monocytes) and cytokines (like interferons) that respond to infections.

4. **Identifying the Third Line of Defense**:
- The third line of defense is the adaptive or acquired immunity, which develops over time through exposure to pathogens or vaccination.

5. **Analyzing the Statements**:
- The first statement claims that the body's first line of defense is the skin, which is true.
- The second statement claims that the second line of defense is skin and phagocytic cells, which is incorrect because the skin is part of the first line of defense.
- The third statement claims that the third line of defense is the immune system, which is correct.

6. **Conclusion**:
- The only wrong statement regarding the lines of defense is the second one, which incorrectly associates the skin with the second line of defense.

### Final Answer:
The wrong statement regarding the lines of defense is: "The second line of defense is skin and phagocytic cells."

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