When a gene exists in more than one form,the different forms are called

The genotypes of a husband and wife are $I^AI^B$ and $I^Ai$. Among the blood types of their children,how many different genotypes and phenotypes are possible?

$A$ man with blood group $B$ marries a woman with blood group $A$ and their first child has blood group $B$. What is the genotype of the child?

What does a gamete contain in a multiple allele system?

The plasma membrane of the red blood cells has ...$A$... polymers that protrude from its surface and the kind of sugar is controlled by the gene. The gene $I$ has three alleles ...$B$... The alleles and produce a slightly different form of the sugars,while allele $i$ doesn't produce any ...$C$...
Choose the correct option for $A, B$ and $C$.

Which of the following is an example of multiple allelism?