Answer:
AB
Explanation:
Blood group is discovered by famous scientist Karl Landsteiner in the year 1990. Co-dominance is the expression of the two alleles in the heterozygotes. In AB type, the two different alleles are present and they are expressed.
However in ABO type, it is govern by three allele namely A, B and O type. If only the antigen A is present, it is called A blood type. When only B antigen is present it is called B blood type and when both A and B are present, it is called AB blood type. And if neither of the antigen are present, it is called the O blood type.
The allele O is of recessive to both the blood type A and B. So a person with O blood type have two copies of O allele. But however A and B blood type are dominant of O, a person with A blood type may have one of the two genotypes -- AO or AA. Similarly, with blood type B, the genotypes are BO or BB.
