Q. A married couple adopted a male child. A few years later, twin boys were born to them. The blood group of the couple is AB positive and O negative. The blood group of the three sons is A positive, B positive, and O positive. The blood group of the adopted son is
A) A positive
B) O positive
C) Cannot be determined on the basis of the given data
D) B positive
✔ Correct Answer: O positive
Exam Insight
In this case, the biological sons' blood groups are determined by the ABO and Rh factor inheritance from the parents, with the first son being A positive, and the second son showing a possible compatibility for a B positive blood group.