Question

Please help! So confused. :(
Blood type in humans is an example of trait that has multiple alleles. The alleles for type A blood and type B blood are codominant, and type O blood is recessive to both type A and type B. If a girl with type AB blood has a brother with type O blood and a sister with type B blood, which of the following genotypes could it be possible for their parents to have?

Answer 1

i thiink the answer would be not positive tho
AB and BO
AB and OO
AO and AB
AO and BO

Answer 2

A. AO and BO
B. AB and OO
C. AB and BO
D. AO and AB

Answer 3

i used this as a reference http://www.hobart.k12.in.us/jkousen/Biology/multalle.htm

Answer 4

what do you mean not positive?

Answer 5

and oh okay, im gonna go to it