Answer:
Depends on the genotype of the parents the child could be any blood type A,B,AB,O. Blood type A & B are dominant over O , so the parents could be heterozygous (genotype AO & BO, they have each the allele for the recessive blood O) and homozygous (genotype AA & BB).
# If the both parents have homozygous (genotype AA & BB) than the offspring will be blood type AB.
# If the parents have heterozygous (AO & BO) then the offspring will be A,B,AB,O.
# If the genotype of parents are AO & BB then the offspring will be AB, B.
# If the genotype of parents are AA &
BO then the offspring will be AB , A.