The Interference Pattern Is from a Convex Lens Placed on a Flat

Multiple Choice

The interference pattern is from a convex lens placed on a flat reflecting surface using a monochromatic light of wavelength λ = 550 nm. The distance between the lens and the flat surface at position A is

A) 275 nm.
B) 550 nm.
C) 687.5 nm.
D) 825 nm.
E) 962.5 nm.