Dihybrid crosses can be conducted with two organisms that are heterozygous for two different traits: SsYy x SsYy for example. Which genotypic ratio shows that genes in dihybrid crosses are inherited according to the principle of independent assortment?
A.
25:25:25:25
B.
50:50
C.
3:1
D.
9:3:3:1
D.
9:3:3:1