The propagation of light ray from a prism is shown below
From the above figure, we can say that minimum value of angle of deviation can only be achieved when A. incident ray and emergent ray are symmetric to the prism. B. the refracted ray inside the prism becomes parallel to its base. C. angle of incidence is equal to angle of emergence. ∴Statement (A), (B) and (C) are true. Note Refracted ray inside the prism is parallel to the base only for equilateral and isosceles prism.