In a double slit interference experiment, `d` is the separation of the slits and D is the distance of the screen from the plane of the slits. When white light is used, a dark band of wavelength `lambda` is formed, directly in front of one of the slits. Then the value of `lambda` is

Options

A. `d^2//D`
B. `D//d`
C. `d//D^2`
D. `d//D`.