A heterozygous, but phenotypically wild-type parrot (gray body and normal wings) was mated to a white parrot with deformed wings. The offspring had the following phenotypic distribution: 720 wild type; 780 white-deformed wings; 280 white-normal wings; 220 gray-deformed wings. What conclusion can be drawn?

A. Color and wing shape are polygenic traits
B. Epistasis has modified a 9:3:3:1 ratio
C. Color and wing shape are linked genes
D. The alles for color and wing shape assort independently from each other
E. Either color or wing shape is sex-linked