JEE Advanced 2016 Paper 1

A transparent slab of thickness d has a refractive index n(z) that increases with z. Here z is the vertical distance inside the slab, measured from the top. The slab is placed between two media with uniform refractive indices n1 and n2(>n1),as shown in the figure. A ray of light is incident with angle θ1 from medium 1 and emerges in medium 2 with refraction angle θf with a lateral displacement l
Which of the following statement(s) is(are) true ?