Light from a Laser $\lambda$ = 640 Nm) Passes Through a Diffraction Grating and Spreads

Multiple Choice

Light from a laser ( $\lambda$ = 640 nm) passes through a diffraction grating and spreads out into three beams as shown in the figure. Determine the spacing between the slits of the grating.

A) 240 nm
B) 410 nm
C) 500 nm
D) 680 nm
E) 800 nm