A Particular Flower Can Be Purple, Blue, Red, or White

A particular flower can be purple, blue, red, or white.Two different pure-breeding white plants are crossed and the F₁ are then crossed to produce an F₂ generation.What might a 9:7 phenotypic ratio in the F₂ indicate?

A) reciprocal recessive epistasis
B) codominance
C) dominant epistasis
D) recessive lethality
E) additivity