A ray of light is incident normally an one face of 30° -60°-90° prism of refractive index immersed in water of refractive index as shown in figure, A) The exit angle o. of the ray is sin B) The exit angle of the ray is sin C) Total internal reflection at point P ceases if refractive index of water is increased to by dissolving some substance D) Total internal reflection at point P ceases if refractive index of water is increased to by dissolving some substance