X-Rays Are Directed Toward a Crystal $\circ$ for Certain Crystallographic Planes

X-rays are directed toward a crystal.The first order diffraction peak appears at 11 ^$\circ$ for certain crystallographic planes.The separation between the planes is 0.512 nm.What is the wavelength of the x-rays?

A) 0.312 nm.
B) 0.216 nm.
C) 0.183 nm.
D) 0.195 nm.
E) 0.140 nm