Number of leucocytes in per mm–3 of blood is –

Options

A. 10000 – 20000
B. 6000 – 8000
C. 15000 – 20000
D. 20000 – 30000

Answer

To determine the number of leucocytes (white blood cells) in per mm³ of blood, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition**: Leucocytes, also known as white blood cells (WBCs), are a crucial part of the immune system. They help the body fight infections and other diseases.

2. **Identify the Normal Range**: The normal count of leucocytes in human blood typically ranges from 5,000 to 8,000 cells per mm³. This is the standard reference range for healthy individuals.

3. **Evaluate the Options**: The question provides several options for the number of leucocytes:
- A) 10,000 to 20,000
- B) 6,000 to 8,000
- C) 15,000 to 20,000
- D) 20,000 to 30,000

4. **Compare Options with Normal Range**:
- Option A (10,000 to 20,000) is above the normal range and indicates a potential infection or other medical condition.
- Option B (6,000 to 8,000) falls within the normal range.
- Option C (15,000 to 20,000) is also above the normal range.
- Option D (20,000 to 30,000) is significantly higher than the normal range.

5. **Select the Correct Answer**: Since the normal count for leucocytes is 5,000 to 8,000, the best answer that fits this range is **Option B: 6,000 to 8,000**.

### Final Answer:
The number of leucocytes in per mm³ of blood is **6,000 to 8,000**.

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