On the basis of the experiment, "To trace the path of a ray of light through a rectangular glass slab", students of a class arrived at which one of the
following conclusions? (A) Angle of incidence is greater than the angle of emergence. (B) Angle of emergence is smaller than the angle of refraction. (C) Emergent ray is parallel to the refracted ray. (D) Incident ray and emergent ray are parallel to each other.