The Diffraction Pattern Shown Was Made on a Screen 6

The diffraction pattern shown was made on a screen 6 meters from a grating.The wavelength of the light was 500 nm.What must have been the separation of the slits in the grating (in mm) ?

A) 0.05
B) 3.00
C) 0.10
D) 0.30
E) More information is needed.