Variable refractive index question [closed]

A ray of light travelling in air is incident at grazing incidence on a slab with variable refractive index, $$n (y) = [k y^{3/2}+ 1]^{1/2}$$ where $$k = 1 m^{-3/2}$$ and follows path as shown in the figure. What is the angle of refraction when the ray comes out. $$(A) 60^°$$
$$(B) 53^°$$
$$(C) 30^°$$
$$(D)$$ No deviation

.................………
My approach:-

Let the angle of emergence br $$r$$
At origin i. e $$y=0$$ $$n_1=1$$ and when $$y=1$$ $$n_2=\sqrt2$$
Using Snell's law $$n_1 \sin90^° = n_2 sinr$$ On solving this I get $$r=45^°$$ but the sad part is that my answer doesn't match with any option.

closed as off-topic by ACuriousMind♦Apr 26 at 16:12

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – ACuriousMind
If this question can be reworded to fit the rules in the help center, please edit the question.

• The ray does not emerge into a medium of index $\sqrt{2}$. – nasu Apr 26 at 16:01
• So what index the ray emerge, I simply put y = 1 in given equation – Abhishek Kumar Apr 26 at 16:03
• Please note that homework-like questions and check-my-work questions are generally considered off-topic here. We intend our questions to be potentially useful to a broader set of users than just the one asking, and prefer conceptual questions over those just asking for a specific computation. – ACuriousMind Apr 26 at 16:12
• @Abhishek The ray emerges in air, according to your image. – nasu Apr 26 at 22:32

Answer is 4) No deviation . For a slab there is no deviation. $$n_1=n_2=1$$ of emergent ray from incident ray.