17. Light travels from material X with an index of refraction of n=1.5 to material Y with an index of refraction of n=2.0. If the speed of light in material Y is v, what is the speed of light in material X ?
(A) 0.56v
(B) 0.75v
(C) 1.33v
(D) 1.78v
(A) 0.56v
(B) 0.75v
(C) 1.33v
(D) 1.78v