Multiple alleles of the ABO blood group gene govern the four major blood types in humans (phenotypes A, B, AB, and O). Alleles I^A and I^B are codominant and allele i^O is recessive to both codominant alleles. A woman of blood type O is suing a man of blood Type AB in paternity suit concerning her child, who is blood Type A.

a) Can this man be the father of her child? Explain.

b) What blood types (of the man) would definitely rule out this man as the father of this woman's Type A child? Explain.

c) Suppose a woman and her child were both of blood Type AB. What possible blood types would you expect to characterize the father of the child? Explain.