The refractive index of medium A with respect to B is 1.25, and that of medium B with respect to C is 1.20. Which of the following correctly lists the speeds of light vA,vB,vC in the three media?
a) vA<vC<vB
b) vA<vB<vC
c) vC<vB<vA
d) vB<vC<vA