Which of the following statements is incorrect ?

Options

A. A persion of 'O' blood group has anti 'A' and anti 'B' antibodies in his blood phasma
B. A person of 'B' blood group can't donate blood to a person of 'A' blood group
C. Bloog group is designated on 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 and their characteristics, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1**: "A person of O blood group has anti-A and anti-B antibodies in his blood plasma."
- **Analysis**: This statement is correct. Individuals with O blood type do indeed have both anti-A and anti-B antibodies in their plasma, which means they cannot receive A or B blood without agglutination occurring.

2. **Statement 2**: "A person of B blood group can't donate blood to a person of A blood group."
- **Analysis**: This statement is also correct. A person with B blood type has anti-A antibodies. If they donate blood to a person with A blood type (who has A antigens), the anti-A antibodies from the B donor will react with the A antigens of the recipient, leading to agglutination, which can be fatal.

3. **Statement 3**: "Blood group is designated on the basis of the presence of antibodies in the blood plasma."
- **Analysis**: This statement is incorrect. Blood groups are determined by the presence of antigens (A and B) on the surface of red blood cells, not by the antibodies present in the plasma. The antibodies are a response to the antigens that are not present in the individual's blood.

4. **Statement 4**: "A person of AB blood group is a universal recipient."
- **Analysis**: This statement is correct. Individuals with AB blood type have both A and B antigens on their red blood cells and do not have anti-A or anti-B antibodies in their plasma. Therefore, they can receive blood from any blood group without the risk of agglutination.

### Conclusion:
The incorrect statement among the options provided is **Statement 3**: "Blood group is designated on the basis of the presence of antibodies in the blood plasma."

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