Which of the following pairs of d - orbitals will have the electron density along the axis?

Those orbitals which have electron densities towards the particular axis are known as axial orbitals. Here, ${\mathrm{d}}_{{\mathrm{z}}^2} \& {\mathrm{d}}_{{\mathrm{x}}^2-{\mathrm{y}}^2}$ are given. They have electron densities towards the particular axis.