According to the given information the genotype of the woman with blood type "AB" would by I^AI^B. The genotype of the man with blood type O would be "ii". Here, the alleles I^A and I^B are dominant over the allele "i".
A cross between parents with genotype I^AI^B and ii would give 50% of children with I^Ai genotype and 50% of children with I^Bi genotype. The children with "I^Ai genotype" would have blood type "A" and the children with I^Bi genotype would have blood type "B". This couple is never likely to have any child with blood type "O" since the mother does not carry allele "i".
