Can someone with type AB blood have a parent O?

No, a person with type AB blood cannot have a parent with type O blood.

A person's blood type is determined by the alleles they inherit from their parents. There are three alleles that determine blood type: A, B, and O. A person with type AB blood has both the A and B alleles. A person with type O blood has neither the A nor the B allele.

In order for a person to have type AB blood, they must inherit the A allele from one parent and the B allele from the other parent. A person with type O blood cannot pass on either the A or the B allele, so they cannot be the parent of a person with type AB blood.