Light Is Reflecting Off a Wedge-Shaped Thin Piece of Glass

Multiple Choice

Light is reflecting off a wedge-shaped thin piece of glass producing bright and dark interference fringes.If a certain location has a bright fringe,a nearby point will have a dark fringe if the thickness of the glass increases by:

A) 1/8 of a wavelength of the light.
B) 1/4 of a wavelength of the light.
C) 1/2 of a wavelength of the light.
D) one wavelength of the light.