In Primroses, the Dominant Allele of Gene K Is Necessary

Multiple Choice

In primroses, the dominant allele of gene K is necessary to synthesize blue flower pigment. Blue pigment synthesis is inhibited by a dominant allele of gene D. In other words, plants with the genotype K- D- will not produce pigment (and their flowers will be white) because of the presence of the D allele.
-If two dihybrid plants (Kk Dd) are crossed, what is the ratio of blue to white offspring in the progeny?

A) 3 blue: 1 white
B) 7 blue: 9 white
C) 4 blue: 12 white
D) 3 blue: 13 white
E) 1 blue: 15 white