Wandering cells are

Options

A. Histiocytes
B. Mast cells
C. Leucocytes
D. All the above .

Answer

### Step-by-Step Solution

1. **Understanding the Term "Wandering Cells":**
- Wandering cells are defined as cells that are not fixed in a specific location within the body. They are capable of moving throughout the tissues.

2. **Identifying Types of Cells:**
- The question provides four options:
1. Hysteresis
2. Mast cells
3. Leukocytes
4. All of the above

3. **Analyzing Each Option:**
- **Hysteresis:** This term does not refer to a type of cell; it is more related to physical systems and not relevant to the context of wandering cells.
- **Mast Cells:** These are a type of immune cell involved in allergic responses and are somewhat fixed in connective tissues, thus not classified as wandering cells.
- **Leukocytes:** These are white blood cells that circulate in the bloodstream and can move into tissues. They are considered wandering cells because they are not fixed and can migrate to sites of infection or injury.

4. **Conclusion:**
- Based on the definitions and characteristics of the cells provided, the correct answer to the question "Wandering cells are" is **Leukocytes**.

### Final Answer:
Wandering cells are **Leukocytes**.

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