Natural killer cells are

Options

A. a type of lymphocyte and are a part of acquired immunity
B. a type of lymphocyte and are a part of innate immunity
C. a type of monocyte and are a part of acquired immunity
D. a type of monocyte and are a part of innate immunity

Answer

**Step-by-Step Solution:**

1. **Understanding Natural Killer Cells**:
- Natural killer (NK) cells are a type of lymphocyte, which are a subset of white blood cells. They play a crucial role in the immune response by identifying and destroying infected or cancerous cells.

2. **Types of Immunity**:
- Immunity can be broadly classified into two categories: innate immunity and acquired (adaptive) immunity.
- Innate immunity is the body's first line of defense and is non-specific, meaning it responds to all pathogens in the same way. It is present from birth.
- Acquired immunity, on the other hand, is pathogen-specific and develops over time as the body is exposed to different pathogens.

3. **Role of Natural Killer Cells**:
- NK cells are part of the innate immune system. They act quickly to eliminate infected or transformed cells without the need for prior sensitization to the pathogen.
- Unlike other lymphocytes, such as B cells and T cells, which are part of the acquired immune response, NK cells do not require prior exposure to a pathogen to be activated.

4. **Conclusion**:
- Based on the information, we can conclude that natural killer cells are a type of lymphocyte and are a part of innate immunity.

**Final Answer**: Natural killer cells are a type of lymphocyte and are a part of innate immunity.

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