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 $$n_1$$ and $$n_2(> n_1)$$, as shown in the figure. A ray of light is incident with angle $$\theta_i$$ from medium 1 and emerges in medium 2 with refraction angle $$\theta_f$$, with a lateral displacement l.

Which of the following statement(s) is(are) true?