select the set of parents that cannot produce child with blood group 'O'

Options

A. (a) `I^Ai × I^Ai`
B. (b) `I^Bi × I^AI^A`
C. (c) `ii × I^Ai`
D. (d) `I^BI^B × I^AI^B`

Answer

To determine which set of parents cannot produce a child with blood group 'O', we need to analyze the genotypes of the parents and understand how blood group inheritance works. Blood groups are determined by the ABO blood group system, which consists of three alleles: A, B, and O.

### Step-by-Step Solution:

1. **Understanding Blood Group Inheritance**:
- Blood group 'O' is represented by the genotype 'ii' (homozygous recessive).
- Blood groups 'A' and 'B' can be either homozygous (AA or BB) or heterozygous (AO or BO).
- Blood group 'AB' is represented by the genotype 'AB'.

2. **Analyzing Each Option**:
- **Option A**: Both parents have blood group A (genotypes could be AA or AO).
- Possible offspring: AA, AO, AO, OO (where OO represents blood group O).
- Conclusion: Can produce blood group O. **Not the answer**.

- **Option B**: One parent has blood group B (genotypes could be BB or BO) and the other has blood group A (genotypes could be AA or AO).
- Possible offspring: AB, AO, BO, BB.
- Conclusion: Cannot produce blood group O. **This is a possible answer**.

- **Option C**: One parent has blood group O (genotype ii) and the other has blood group A (genotypes could be AA or AO).
- Possible offspring: AO, OO (where OO represents blood group O).
- Conclusion: Can produce blood group O. **Not the answer**.

- **Option D**: One parent has blood group B (homozygous BB) and the other has blood group AB.
- Possible offspring: AB, AB, BB, BB.
- Conclusion: Cannot produce blood group O. **This is a possible answer**.

3. **Final Conclusion**:
- The sets of parents that cannot produce a child with blood group 'O' are **Option B** and **Option D**.