ABO blood groups in humans are controlled by the gene I. It has three alleles - `I^(A), I^(B)` and i. Since there are three different alleles, six different grnotypes are possible. How many phenotypes can occur?

Options

A. Three
B. One
C. Four
D. Two

Answer

C

Explanation

The ABO blood group system has at least 6 genotypes. On the basis of presence or absence of antigens and antibodies, four blood groups (phenotypes) have been differentiated-A, B, AB and O blood group. In ABO blood group system, inheritance of grouping is controlled by a single autosomal gene on chromosome 9 with three major alleles A, B and O (`I^(A) , I^(B)` and `I^(O)`).