A child of blood group 'O' cannot have parents of blood groups:

Options

A. AB and AB/O
B. A and B
C. B and B
D. O and O

Explanation

To determine which blood groups cannot have a child with blood group 'O', we need to understand the inheritance patterns of blood groups, specifically the ABO blood group system.

### Step-by-Step Solution:

1. **Understand the ABO Blood Group System**:
- Blood groups are determined by the presence of antigens on the surface of red blood cells. The main types are A, B, AB, and O.
- The genotypes for these blood groups are:
- A: \(I^A I^A\) or \(I^A i\)
- B: \(I^B I^B\) or \(I^B i\)
- AB: \(I^A I^B\)
- O: \(ii\)

2. **Identify the Genotypes of Parents**:
- For a child to have blood group 'O' (genotype \(ii\)), each parent must contribute an 'i' allele.
- Therefore, both parents must have at least one 'i' allele in their genotype.

3. **Analyze Possible Parent Combinations**:
- **O and O**: Both parents are \(ii\), so the child can be \(ii\) (O).
- **A and A**: Possible genotypes are \(I^A I^A\) or \(I^A i\). No 'i' allele means the child cannot be O.
- **B and B**: Possible genotypes are \(I^B I^B\) or \(I^B i\). No 'i' allele means the child cannot be O.
- **A and B**: Possible genotypes are \(I^A I^B\) or \(I^A i\) and \(I^B i\). The child could be A, B, AB, or O, depending on the specific alleles contributed.
- **AB and any group (including O)**: The AB parent (\(I^A I^B\)) cannot contribute an 'i' allele, thus the child cannot be O.

4. **Conclusion**:
- The combinations that cannot produce a child with blood group 'O' are:
- AB and AB
- AB and A
- AB and B
- A and A
- B and B

### Final Answer:
A child of blood group 'O' cannot have parents of blood groups AB and AB, A and A, B and B, or AB and A/B.