Two Slits Are Illuminated with Green Light $\lambda$ = 540 Nm)The Slits Are 0

Multiple Choice

Two slits are illuminated with green light ( $\lambda$ = 540 nm) .The slits are 0.05 mm apart and the distance to the screen is 1.5 m.At what distance (in mm) from the central maximum on the screen is the average intensity 50% of the intensity of the central maximum?

A) 1
B) 3
C) 2
D) 4
E) 0.4