Green Light Having Wavelength of 550 Nm (In Air) Is

Multiple Choice

Green light having wavelength of 550 nm (in air) is vertically incident on a thin film of water that has an index of refraction of 1.30. The film of water rests above a plastic pane (having an index of refraction of 1.22) . The green light is brightly reflected. The minimum (nonzero) thickness of the film of water is

A) 212 nm.
B) 450 nm.
C) 423 nm.
D) 108 nm.