Refractive indices of four media A, B, C and D are given below:

Medium	Refractive Index
A	1.33
B	1.44
C	1.52
D	1.65

In which of these four media is the speed of light (i) maximum, and (ii) minimum?

The refractive index of a medium is related to the speed of light as follows: 

$Refractive\ index\ of\ a\ medium=\frac {Speed\ of\ light\ in\ vacuum}{Speed\ of\ light\ in\ medium}$

Since the speed of light in vacuum is constant, the refractive index becomes inversely proportional to the speed of light in a medium (if the speed of light in a medium increases then the value of the refractive index decreases and vice-versa).

Therefore,

(i) The speed of light is maximum in a medium that has the lowest refractive index, which is medium A, here.

(ii) The speed of light is minimum in a medium that has the highest refractive index, which is medium D, here.