A man whose blood group is heterozygous B is married to a woman whose blood up is also heterozygous B. 

Which of the following statements is correct about the blood group of their four offspring?

A.

Three of them belong to blood group B

B.

Three of them belong to blood group O

C.

None of them belongs to blood group O

D.

Two of them belong to blood group B

Correct answer is A

No explanation has been provided for this answer.