In people sickle cell disease is expressed codominantly. When an individual is heterozygous they have both normal and sickled cells, but has only sickled cells when they have only recessive alleles. What is the phenotypic ratio of offspring with two heterozygous parents?
A. 1 all round cells : 1 mixed round and sickled cells : 0 all sickled cells
B. 1 all round cells : 2 mixed round and sickled cells : 1 all sickled cells
C. 1 all round cells : 0 mixed round and sickled cells : 1 all sickled cells
D. 3 all round cells : 0 mixed round and sickled cells : 1 all sickled cells
