A ray of light passes from vaccum into a medium of refractive index n. If the angle of incidence is twice the angle of refraction, then the angle of incidence is
A. `sin^(-1)((n)/(2))`
B. `2sin^(-1)((n)/(2))`
C. `cos^(-1)((n)/(2))`
D. `2cos^(-1)((n)/(2))`
