Ram's blood cells do not agglutinate with addition of either anti-A or anti-B serum. However, serum collected from Ram causes agglutination of RCBs collected from another person.
Based on the above information, blood group of Ram is most likely.

Options

A. A
B. B
C. O
D. AB

Answer

To determine Ram's blood group based on the information provided, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Agglutination**:
- Agglutination occurs when antibodies in a serum bind to specific antigens on the surface of red blood cells (RBCs). If agglutination happens, it indicates the presence of corresponding antigens.

2. **Analyzing Ram's Blood Cells**:
- The question states that Ram's blood cells do not agglutinate with either anti-A or anti-B serum. This means that there are no A antigens or B antigens present on Ram's RBCs.

3. **Conclusion from Agglutination Test**:
- Since there is no agglutination with anti-A serum, Ram's blood does not have A antigens.
- Similarly, since there is no agglutination with anti-B serum, Ram's blood does not have B antigens.

4. **Identifying Ram's Blood Group**:
- The absence of both A and B antigens indicates that Ram's blood group is O. Blood group O is characterized by the lack of A and B antigens on the RBCs.

5. **Analyzing Ram's Serum**:
- The question also mentions that serum collected from Ram causes agglutination of RBCs from another person. This means that Ram's serum contains antibodies against A and B antigens (anti-A and anti-B).
- Since Ram's blood group is O, he would naturally produce both anti-A and anti-B antibodies.

### Final Conclusion:
Based on the analysis, Ram's blood group is most likely **O**.