The refractive index of space changes with $y$ , whose function is given as

$\mu \left(y\right)=\{\begin{array}{ccc}1& \text{ if }& y\le 0\\ k{y}^2& \text{ if }& 0<y\le y_0\\ \frac{\mathcal{l}}{y^2}& \text{ if }& y_0<y\le 2y_0\end{array}$

where k  and  $\mathcal{l}$  are positive constant. A light ray is incident at point A as shown in figure. When the ray reaches to point B, it becomes parallel to xz-plane. Choose the correct statement.