Answer:
In humans, blood group is determined by three alleles [tex]I^{A}[/tex], [tex]I^{B}[/tex], and [tex]i[/tex].
[tex]I^{A}[/tex] and [tex]I^{B}[/tex] are co-dominant whereas [tex]i[/tex] is recessive to other two.
Thus, if a person with blood group O produces offspring with blood group B then the other parent must contain [tex]I^{B}[/tex] allele.
The genotype of other person can be [tex]I^{A}I^{B}[/tex], [tex]I^{B}I^{B}[/tex], or [tex]I^{B}i[/tex].
There is only one condition in which the person can have offspring with blood group O that is, when the other parent is [tex]I^{B}i[/tex].
In this condition, the probability of an offspring to have blood group O is 50%.
In other conditions, the probability of an offspring to have blood O is 0%.
