Jessica is blood type A and her husband Graham is blood type O. She is worried because they are pregnant and their future child has a rare disorder which will require him to need regular blood transfusions. Jessica worries that if their son ends up with type O blood, like his father, it will be hard to get the necessary regular blood transfusions because people with O blood can only accept O blood. What is the likelihood of their child having blood type O? Use punnett squares to show all possibilities.