RBCs are

Options

A. Differentiated cells
B. Undifferentiated cells
C. Dedifferentiated cells
D. Dead cells

Answer

To answer the question "RBCs are:", we will analyze the characteristics and classification of red blood cells (RBCs).

### Step-by-Step Solution:

1. **Understanding RBCs**:
- Red blood cells, or erythrocytes, are the cells responsible for transporting oxygen from the lungs to the rest of the body and returning carbon dioxide from the body back to the lungs.

2. **Formation of RBCs**:
- RBCs are produced in the bone marrow from precursor cells. Initially, they start as undifferentiated cells known as hematopoietic stem cells.

3. **Differentiation Process**:
- As these stem cells undergo differentiation, they develop into erythroblasts. During this stage, they contain a nucleus and mitochondria.

4. **Maturation of RBCs**:
- As erythroblasts mature into red blood cells, they lose their nucleus and mitochondria. This loss is crucial as it allows more space for hemoglobin, the protein that carries oxygen.

5. **Final Classification**:
- After maturation, the cells that we recognize as RBCs are fully differentiated. They are specialized for their specific function of oxygen transport.

6. **Conclusion**:
- Therefore, RBCs are classified as differentiated cells because they have undergone a specific process of development and specialization from stem cells to their mature form.

### Final Answer:
RBCs are **differentiated cells**.

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