An Oil Film (N = 1

An oil film (n = 1.48) of thickness 290 nm floating on water is illuminated with white light at normal incidence.What is the wavelength of the dominant color in the reflected light?

A) Green (541 nm)
B) Blue-green (493 nm)
C) Violet (404 nm)
D) Yellow (572 nm)
E) Blue (470 nm)