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?
[UPSC Civil Services Exam – 2011 Prelims]
(a) O Positive
(b) A Positive
(c) B Positive
(d) Cannot be determined on the basis of the given data
Here, the blood group of the couple is AB positive and O negative, then their biological sons blood group must be A or B. Hence we can say that the blood group of the adopted son is O positive.