Answer:
There is a 0% chance that a child can donate blood
Explanation:
Since the O gene is recessive, if the mother is type O then she can only give the O gene.
If the father is homozygous for gene B, then he can only give that gene B which is the only one that has
Since gene B is dominant and your children will have an OB combination, then all your children will have type B blood.
To donate blood to a person O, you need to have blood type O. So none of your children can donate blood
