In an octahedral crystal field, the correct set of low-energy orbitals are
 

Considering a molecule with octahedral geometry, along the x, y, and z axes, ligands approach the metal ion.

Orbitals that are located along these axes i.e. ${\mathrm{d}}_{{\mathrm{x}}^2-{\mathrm{y}}^2}, {\mathrm{d}}_{{\mathrm{z}}^2}$are more repellent. These orbitals demand more energy to maintain an electron in them than one of the other orbitals would. The energy levels of the d-orbitals separate as a result. This is "crystal field splitting". 

Hence the correct answer is  ${\mathrm{d}}_{\mathrm{xy}}, {\mathrm{d}}_{\mathrm{xz}}, {\mathrm{d}}_{\mathrm{yz}}$