What blood type will a child have if one parent has type A blood and the other has type O blood?

Under normal circumstances, a child born to parents with blood type A and blood type O can have either blood type A or blood type O. The detailed explanation is as follows:

The inheritance of the human ABO blood group system is controlled by three alleles—A, B, and O—located on chromosome 9. Generally, there are six possible ABO genotypes: AA, AO, BB, BO, AB, and OO. When one parent has blood type A and the other has blood type O, two genetic combinations are possible: AO and OO, or AA and OO. If the combination is AO and OO, the child will typically have blood type A. However, if the combination is AA and OO, the child may have either blood type O or blood type A. Therefore, overall, children born to parents with blood type A and blood type O usually have either blood type A or blood type O.

In summary, the child of an A-type and an O-type parent can only have one of two blood types. However, note that in certain situations, such as after hematopoietic stem cell transplantation, a person's blood type may change.