Robert and Megan are brother and sister,and both have type O blood.They know that their mother has type A blood,but they don't know their father's blood type.Using what they know about their own blood types and their mother's,they know that their father's blood type
A)could be A, B, O, or AB.
B)must be O.
C)must be A.
D)could be A or O.

Question

Robert and Megan are brother and sister,and both have type O blood.They know that their mother has type A blood,but they don't know their father's blood type.Using what they know about their own blood types and their mother's,they know that their father's blood type​ 
A)could be A, B, O, or AB. 
B)must be O. 
C)must be A. 
D)could be A or O.

Quizplus · Accepted Answer

Since both Robert and Megan have type O blood, they must have inherited an O allele from each parent. Their mother has type A blood, meaning she must have at least one A allele. Therefore, their father can either be AO (carrying an A and an O allele) or OO (carrying two O alleles). So, their father's blood type could be A or O.

Robert and Megan Are Brother and Sister,and Both Have Type