[单选题]
Monochromatic light of wavelength 500 nm is incident normally9k*lpme a) c:a on a gratq; nnq+rb(y9u ing. If the third-order maximum of the diff9+qqy(r;bn u nraction pattern is observed at $32.0^{\circ}$, what is the grating constant (distance between the slits)?
A. $0.93 \; mm$
B. $1.4 \; mm$
C. $2.8 \; mm$
D. $8.5 \; mm$
