Explanation:
Let's reflect on heredity:
Females are birthed when two X chromosomes are paired up (XX).
Males are birthed when one X chromosome and one Y chromosome are paired up (XY).
If the woman has blood type AB and her husband has blood type O, their children could have any blood type associated with that. Try setting up a punnett square!
You will get:
2/4 AO
2/4 BO
So, the odds of a child getting OO are 0.