In a Young's Double-Slit Experiment, the Separation Between Slits Is $\lambda$

Multiple Choice

In a Young's double-slit experiment, the separation between slits is d and the screen is a distance D from the slits.D is much greater than d and $\lambda$ is the wavelength of the light.The number of bright fringes per unit length on the screen is:

A) "Dd/ $\lambda$ "
B) "D $\lambda$ /d"
C) "D/d $\lambda$ "
D) " $\lambda$ /Dd"
E) "d/D $\lambda$ "