Answer:
The answer is below
Explanation:
The possible phenotypes of the mother can be any of the following
AA - A phenotype
AB - AB phenotype (here the mother must have contributed an A gene for it to be possible)
AO - A phenotype (here the mother may have contributed any of the A or O gene.)
BO - B phenotype (here, the mother would only need to contribute O gene for this to be possible)