What are the products of the $I^A$ and $I^B$ alleles?

Mother is homozygous for blood group $B$,and father has blood group $A$ (genotype unknown). Therefore,the possible blood groups in the progeny are:

$A$ pair of contrasting characters is termed as

The offspring produced from a marriage have only $O$ or $A$ blood groups. Of the genotypes given below,the possible genotypes of the parents would be

$A$ man with blood group $A$ marries a woman with blood group $B$. What are all the possible blood groups of their offspring?

$ABO$ blood group is a good example of: