For safe blood transfusion, donor's antigen must be compatible with recipient's antibody.

Explanation

### Step-by-Step Solution

1. **Understanding Blood Groups**: 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 system is the ABO system, which includes four blood types: A, B, AB, and O. Additionally, there is the Rh factor, which can be positive (+) or negative (-).

2. **ABO Blood Group Antigens and Antibodies**:
- **Blood Group A**: Has A antigens on RBCs and B antibodies in plasma.
- **Blood Group B**: Has B antigens on RBCs and A antibodies in plasma.
- **Blood Group AB**: Has both A and B antigens on RBCs and no antibodies in plasma.
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