Which of the following statements is incorrect ?

Options

A. A preson of 'O' blood group has anti 'B' antibodies in his blood plasma.
B. A person of 'B' blood group can't donate to a person of 'A' blood group
C. Blood group is designated of the basis of the presence of antibodies in the blood plasma
D. A person of AB blood group is universal recipient

Explanation

To determine which statement is incorrect regarding blood groups, we will analyze each option based on our understanding of the ABO blood group system.

### Step-by-Step Solution:

1. **Understanding Blood Group O:**
- A person with blood group O has no antigens (A or B) on the surface of their red blood cells (RBCs).
- However, they have both anti-A and anti-B antibodies in their plasma.
- **Conclusion:** The statement that a person of blood group O has anti-B antibodies in their blood plasma is **correct**.

2. **Understanding Blood Group B:**
- A person with blood group B has B antigens on their RBCs and anti-A antibodies in their plasma.
- If a person with blood group B donates blood to a person with blood group A, the anti-A antibodies in the blood group B recipient will react against the A antigens in the blood group A recipient.
- **Conclusion:** The statement that a person of blood group B cannot donate blood to a person of blood group A is **correct**.

3. **Understanding Blood Group Designation:**
- Blood group designation is based on the presence or absence of antigens (A and B) on the surface of RBCs, not on the antibodies present in the plasma.
- The ABO blood grouping system classifies blood based on these antigens.
- **Conclusion:** The statement that blood group is designated on the basis of the presence of antibodies in the blood plasma is **incorrect**.

4. **Universal Donor and Recipient:**
- Blood group O is known as the universal donor because it has no A or B antigens, allowing it to be transfused to any blood group without causing an immune reaction.
- Blood group AB is known as the universal recipient because it has both A and B antigens and does not have anti-A or anti-B antibodies, allowing it to receive blood from any group.
- **Conclusion:** The statements regarding the universal donor and recipient are **correct**.

### Final Conclusion:
The incorrect statement among the options provided is the one that claims blood group is designated based on the presence of antibodies in the blood plasma. Therefore, the answer is **option 3**.

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