Which statement is true ?

Options

A. RBCs are devoid of nucleus in most of the mammals
B. In adult man 5 to 5.5 million RBCs/mm3 are present
C. Erythrocytes are the most abundant cells in blood and constitute almost 45 present of the blood
D. All statements are true

Answer

To determine which statement is true regarding red blood cells (RBCs) and their characteristics, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Analyze the first statement**: "RBCs are devoid of nucleus in most mammals."
- **Explanation**: In most mammals, red blood cells do not have a nucleus. This adaptation allows for more space to be occupied by hemoglobin, which is crucial for oxygen transport.
- **Conclusion**: This statement is **true**.

2. **Analyze the second statement**: "An adult man has 5.5 million red blood cells per cubic millimeter."
- **Explanation**: The normal range of red blood cells in an adult male is approximately 4.7 to 6.1 million cells per cubic millimeter, making this statement accurate.
- **Conclusion**: This statement is **true**.

3. **Analyze the third statement**: "Erythrocytes are the most abundant cells in our blood and they constitute 45% of blood volume."
- **Explanation**: Erythrocytes (red blood cells) are indeed the most abundant cells in the blood and typically make up about 45% of the total blood volume in a healthy individual.
- **Conclusion**: This statement is **true**.

4. **Analyze the fourth statement**: "All of the above statements are true."
- **Explanation**: Since we have established that the first three statements are true, this statement must also be true.
- **Conclusion**: This statement is **true**.

### Final Answer:
All statements provided are true. Therefore, the appropriate answer is option 4.

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