Final answer:
Their children may have all blood types EXCEPT Type O.
Step-by-step explanation:
Blood type inheritance follows the principles of Mendelian genetics. The ABO blood group system involves three main alleles: A, B, and O. Individuals inherit one allele from each parent, determining their blood type (A, B, AB, or O). The Rh factor is inherited independently, leading to positive or negative blood types.
Type O is the blood type that their children may NOT have. When a man with Type A blood (genotype of AO) marries a woman with Type AB blood (genotype of AB), their children can have blood types A, B, or AB. This is because type A blood and type B blood are co-dominant, meaning both alleles are expressed in individuals with AB blood type. Type O blood, on the other hand, is recessive and would not be present in their children.