Chromosomes, genes and proteins — practice question

In one family, the two parents have blood groups A and B, and the three children have blood groups B, B and O. What are the genotypes of the parents?

• A$I^A I^A$ and $I^B I^B$
• B$I^A I^B$ and $I^A I^o$
• C$I^A I^o$ and $I^B I^o$
• D$I^B I^o$ and $I^B I^A$