Mark the odd one:

Options

A. Monocytes
B. Lymphocytes
C. Neutrophils
D. Erythrocytes

Answer

**Step-by-Step Solution:**

1. **Identify the Options**: The options given are:
- A) Monocyte
- B) Lymphocyte
- C) Neutrophil
- D) Erythrocyte

2. **Classify the Cells**:
- Monocytes, lymphocytes, and neutrophils are types of white blood cells (WBCs), also known as leukocytes.
- Erythrocytes, on the other hand, are red blood cells (RBCs).

3. **Determine the Function**:
- Erythrocytes (RBCs) are primarily responsible for the transport of gases (oxygen and carbon dioxide) in the blood.
- White blood cells (WBCs) are involved in the immune response and help fight infections.

4. **Identify the Odd One Out**:
- Since monocytes, lymphocytes, and neutrophils are all WBCs, while erythrocytes are RBCs, the odd one out is D) Erythrocyte.

5. **Conclusion**: The answer to the question is D) Erythrocyte, as it is the only option that is not a type of white blood cell.

---