X-Rays of Fixed Wavelength Yield a First-Order Maximum at a Grazing

Multiple Choice

X-rays of fixed wavelength yield a first-order maximum at a grazing angle of 12 $^{\circ}$ .At what angle would one expect to find the corresponding 3^rd order maximum?

A) 4.0 $^{\circ}$
B) 12 $^{\circ}$
C) 36 $^{\circ}$
D) 39 $^{\circ}$
E) more information is needed