A square planar complex is formed by hybridisation of which of the following atomic orbitals ?

A square planar complex is formed by hybridization of $\mathrm{s},{\mathrm{p}}_{\mathrm{x}},{\mathrm{p}}_{\mathrm{y}},{\mathrm{d}}_{{\mathrm{x}}^2-{\mathrm{y}}^2}$ atomic orbitals. All these orbitals lie in the xy plane. Four ligands also lie in the xy plane. This results in maximum overlap.

Hence , the correcct option (B).