Inheritance — practice question

The father’s blood group is AB and the mother’s blood group is O. What ratio of blood groups is expected among the offspring?

• A$1 : 1$ A : B
• B$1 : 1$ AB : O
• C$1 : 1 : 1$ A : B : O
• D$1 : 1 : 1 : 1$ A : B : AB : O