Human blood grouping is ABO instead of ABC because O in it refers to

Options

A. No antigen A or B on RBCs
B. Other antigens besides A and B
C. Overdominance of its gene over A and B
D. One antibody only either anti-A or anti-B

Answer

**Step-by-Step Solution:**

1. **Understanding Blood Groups**: Human blood groups are classified based on the presence or absence of specific antigens on the surface of red blood cells (RBCs). The main blood group systems are A, B, AB, and O.

2. **Identifying Antigens**: In the ABO blood group system:
- Blood group A has A antigens.
- Blood group B has B antigens.
- Blood group AB has both A and B antigens.
- Blood group O has neither A nor B antigens.

3. **Significance of Blood Group O**: The blood group O is unique because it does not have any A or B antigens on the RBCs. This absence of antigens is crucial for blood transfusions, as it means that individuals with blood group O can donate blood to any other blood group without the risk of an immune reaction.

4. **Antibodies in Blood Group O**: While blood group O does not have A or B antigens, it contains antibodies against both A and B antigens. This means that individuals with blood group O can only receive blood from other group O donors.

5. **Conclusion**: The reason the human blood grouping system is referred to as ABO instead of ABC is that the "O" represents the absence of both A and B antigens on the RBCs. Therefore, the correct answer to the question is that O refers to "no antigen A or B on RBC".

**Final Answer**: O in the blood group refers to "no antigen A or B on RBC".

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