Read the following statements (A-D) :
A. RBCs are the most abundant of all the cells in blood
B. A healthy adult man has on an average 5 billions to 5.5 billions of RBCs `mm^(3)` of blood
C. RBCs are formed in liver in the adults
D. RBCs are devoid of nucleus in most of the mammals and are biconcave in shape
How many of the above statements are correct :

Options

A. Four
B. Three
C. Two
D. One

Answer

To determine how many of the statements (A-D) are correct, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A: "RBCs are the most abundant of all the cells in blood."**
- This statement is **correct**. Red blood cells (RBCs) are indeed the most abundant cells in the blood, responsible for transporting oxygen.

2. **Statement B: "A healthy adult man has on an average 5 billion to 5.5 billion of RBCs `mm^(3)` of blood."**
- This statement is **incorrect**. The average count of RBCs in a healthy adult male is approximately 4.5 to 5.9 billion cells per cubic millimeter (mm³) of blood, not 5 to 5.5 billion.

3. **Statement C: "RBCs are formed in liver in the adults."**
- This statement is **incorrect**. In adults, RBCs are primarily formed in the red bone marrow, not the liver. The liver is involved in the formation of RBCs during fetal development.

4. **Statement D: "RBCs are devoid of nucleus in most of the mammals and are biconcave in shape."**
- This statement is **correct**. In most mammals, mature RBCs lack a nucleus and have a biconcave shape, which helps in maximizing surface area for gas exchange.

### Summary of Statements:
- **Correct Statements:** A, D
- **Incorrect Statements:** B, C

### Conclusion:
Out of the four statements, **2 statements (A and D) are correct**.

### Final Answer:
**2 statements are correct.**

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