A ray of light passes from vacuum to a medium of refractive index n. The angle of incidence is found to be twice the angle of refraction. The angle of incidence is
(A) cos-1\(\left(\cfrac n2\right)\)
(B) cos-1 (n)
(C) 2cos-1 \(\left(\cfrac n2\right)\)
(D) 2sin-1\(\left(\cfrac n2\right)\)