Diapedesis is `:-`

Options

A. A type of amoeboid movement
B. Movement of some WBC to tissue through the wall of blood capillary to destroy harmful bacteria
C. A type of movement of hydra
D. Filtration process of urea in kidney

Answer

**Step-by-Step Solution:**

1. **Definition of Diapedesis**: Diapedesis refers to the process by which white blood cells (WBCs) move out of the bloodstream and into surrounding tissues.

2. **Mechanism of Diapedesis**: This process occurs primarily in the capillaries, where the walls are thin enough to allow WBCs to pass through. As blood flows through these capillaries, some WBCs can squeeze through the endothelial cells that line the capillary walls.

3. **Purpose of Diapedesis**: The primary function of diapedesis is to enable WBCs to reach sites of infection or injury in the tissues. Once outside the bloodstream, these cells can target and destroy harmful bacteria or pathogens that may be present in the tissues.

4. **Correct Option Identification**: Among the options provided:
- Option 1: A type of amoeboid movement - Incorrect.
- Option 2: Movement of WBC to tissue through the wall of blood capillary to destroy harmful bacteria - Correct.
- Option 3: A type of movement of hydra - Incorrect.
- Option 4: Filtration process of urea and kidney - Incorrect.

5. **Conclusion**: The correct answer is Option 2, which accurately describes diapedesis as the movement of WBCs from the bloodstream into tissues to combat infections.

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