There is 25% chances for delivering a baby with A-ve.
Explanation:
AB+ is a dominant blood group and O is a recessive blood group. To understand that Jill has AB+ blood type with her father having B- blood type she should have acquired her AB+ from her mother who had A+ blood type.
When mother has this dominant AB+ blood type and father with the O- Recessive blood type there are likely chances only for the dominant alleles to take charge over the recessive ones. Hence there is a chance of the babies to have both A- , A+ blood group and B+ ve or B– ve blood group.
As the mother has her Rh- ve inscribed in her DNA from her father she is a carrier and when joined with Rh- ve from her husband there are 25% chances for delivering a baby with A-ve.