$A$ monochromatic light wave is incident normally on a glass slab of thickness $d$,as shown in the figure. The refractive index of the slab increases linearly from $n_1$ to $n_2$ over the height $h$. Which of the following statement$(s)$ is (are) true about the light wave emerging out of the slab?

• A
  $A$ It will deflect up by an angle $\tan^{-1}\left[\frac{(n_2^2-n_1^2)d}{2h}\right]$
• B
  $B$ It will deflect up by an angle $\tan^{-1}\left[\frac{(n_2-n_1)d}{h}\right]$
• C
  $C$ It will not deflect.
• D
  $D$ The deflection angle depends only on $(n_2-n_1)$ and not on the individual values of $n_1$ and $n_2$.