In two separate set-ups of the Young's double slit experiment, fringes of equal width are observed when lights of wavelength in the ratio of `1:2` are used. If the ratio of the slit separation in the two cases is `2:1`, the ratio of the distance between the plane of the slits and the screen in the two set-ups are

Options

A. `1:1`
B. `1:4`
C. `2:1`
D. `4:1`

Answer

D