Respuesta :
One of her parents had type B blood and the other type A blood.
Answer:
One of her parents had at least one A allele and the other at least one B allele.
Explanation:
ABO blood group is regulated by gene "I" with three alleles: I^A, I^B and i. Since alleles I^A and I^B are codominant over each other, genotype I^A I^B gives "AB" blood type. The genotype of woman with AB blood type is "I^A I^B" which means that she has received one A allele from one parent and one B allele from other parent. Therefore, one of her parents had at least one A allele and the other at least one B allele.