To the birth of a child with blood type A to a mother with blood type B If the father has blood type AB, which of the following statements is correct about the mother?
A. She contributes an IB allele, which is recessive to the father's IA allele
B. She contributes an i allele, which is recessive to the father's IA allele
C. She contributes an IB allele, which is codominant to the father's IA allele
D. She contributes an i allele, which is codominant to the father's IB allele
E. She is homozygous for the IB allele.