The most popularly known blood grouping is the ABO grouping. It is named ABO and not ABC, because "O" in it refers to having

Options

A. One antibody only-either anti-A or anti-B on the RBCs
B. No antigens A and B on RBCs
C. Other antigens besides A and B on RBCs
D. Overdominance of this type of the genes for A and B types

Answer

To answer the question about why the ABO blood grouping is named as such, we need to understand the characteristics of the blood groups involved, particularly focusing on the "O" group.

### Step-by-Step Solution:

1. **Understanding Blood Groups**: The ABO blood grouping system consists of four main blood groups: A, B, AB, and O. Each of these groups is determined by the presence or absence of specific antigens on the surface of red blood cells (RBCs).

2. **Identifying Antigens**:
- **Blood Group A**: Has A antigens on the RBCs.
- **Blood Group B**: Has B antigens on the RBCs.
- **Blood Group AB**: Has both A and B antigens on the RBCs.
- **Blood Group O**: Has no A or B antigens on the RBCs.

3. **Understanding the "O" Group**: The "O" in the ABO system indicates the absence of both A and B antigens on the RBCs. This is a crucial distinction that differentiates it from the other blood groups.

4. **Conclusion**: Therefore, the reason the blood grouping is referred to as ABO and not ABC is that the "O" signifies the absence of antigens A and B on the RBCs. This absence is what characterizes the O blood group.

5. **Final Answer**: The correct option is that "O" refers to having no antigens A and B on RBCs.