A ray of light passes through four transparent media with refractive Indices μ1, μ2,μ3,μ4 as shown in figure. The surface of all media are parallel if the emergent ray CD is parallel to incident ray AB, we must have
(a) μ1 = μ3
(b) μ2 =μ3
(c) μ3= μ4
(d) μ4=μ1