Humans have acquired immune system that produces antibodies to neutralize pathogens. Still innate immune system is present at the time of birth because it

Options

A. (a) is very specific and uses different macrophages.
B. (b) produces memory cells for mounting fast secondary response.
C. (c) has monocytes which phagocytose and destroy microbes
D. (d) provides passive immunity.

Answer

To answer the question regarding why the innate immune system is present at the time of birth, we will analyze the options provided and determine which one accurately describes the role of the innate immune system.

### Step-by-Step Solution:

1. **Understanding the Immune Systems**:
- The human immune system consists of two main types: the innate immune system and the acquired (adaptive) immune system.
- The **innate immune system** is the first line of defense and is present at birth. It includes physical barriers (like skin), chemical barriers (like mucus), and various immune cells (like monocytes and macrophages).
- The **acquired immune system** develops over time as the body encounters pathogens and is responsible for producing specific antibodies and memory cells.

2. **Analyzing the Options**:
- **Option A**: "Very specific and uses different macrophages."
- This statement is incorrect because the innate immune system is not specific; it provides a general defense against pathogens.
- **Option B**: "Produces memory cells for mounting fast secondary response."
- This is also incorrect as memory cells are a feature of the acquired immune system, not the innate immune system.
- **Option C**: "Has monocytes which phagocytose and destroy microbes."
- This statement is correct. Monocytes are part of the innate immune system and play a crucial role in phagocytosing (engulfing and destroying) pathogens.
- **Option D**: "Provide passive immunity."
- This is incorrect because passive immunity is typically provided through maternal antibodies or immunization, not directly by the innate immune system.

3. **Conclusion**:
- The correct answer is **Option C**: "Has monocytes which phagocytose and destroy microbes." This highlights the role of the innate immune system in providing immediate defense against pathogens at the time of birth.

### Final Answer:
The innate immune system is present at the time of birth because it has monocytes which phagocytose and destroy microbes (Option C).