In most of the mammals, RBCs have

Options

A. Nuclei
B. No nuclei
C. No mitrochondria
D. Both (2) & (3)

Answer

**Step-by-Step Solution:**

1. **Understanding the Structure of RBCs**: Red Blood Cells (RBCs), also known as erythrocytes, are specialized cells in the blood responsible for transporting oxygen from the lungs to the body tissues and returning carbon dioxide from the tissues back to the lungs.

2. **Presence of Nucleus**: In most mammals, mature RBCs do not have a nucleus. This is because the absence of a nucleus allows more space for hemoglobin, the protein that carries oxygen, thus increasing the oxygen-carrying capacity of the blood.

3. **Absence of Mitochondria**: Mature RBCs also lack mitochondria. If mitochondria were present, they would consume some of the oxygen that RBCs are supposed to transport. Therefore, the absence of mitochondria ensures that all the oxygen carried by RBCs is delivered to the tissues without being used up by the RBCs themselves.

4. **Other Organelles**: Besides the nucleus and mitochondria, mature RBCs do not contain other organelles like the Golgi apparatus or endoplasmic reticulum. This further maximizes space for hemoglobin and enhances their efficiency in oxygen transport.

5. **Conclusion**: Based on the above points, the correct answer to the question is that in most mammals, RBCs have no nucleus and no mitochondria. Therefore, the right option is both two and three.

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