A boy has I (I0I0) blood group and his sister has IV (IAIB) blood group. What blood groups do their parents have?

Answer options

1. I (I0I0) and IV (IAIB)
2. II (IAIA) and III (IBI0)
3. I (I0I0) and III (IBI0)
4. II (IAIB) and III (IBI0)
5. III (IBI0) and IV (IAIB)

Explanation

|A|O: |B|O. Gives: |A|B |A|O |B|O |O|O. This is the only combination that can produce the above blood groups of the children.