Answer:
The children could have blood types A, B or AB. Its NOT possible for the children to have type O.
Step-by-step explanation:
The question does not indicate whether the man with type B blood is BB or BO. Therefore there are two possible Punnett squares. As you can see from the attached image, a child could have AB, BB, AO, or BO. Since A and B are dominant over O the AO blood type results in type A blood and the BO blood type results in type B blood. AB would be type AB blood. and BB would be type B blood.