Identify the pairs which are not of isotopes?

Show the distribution of electrons in oxygen atom (atomic number $8$) using the orbital diagram. 

Which of the following orbitals are degenerate?

$3{\mathrm{d}}_{\mathrm{xy}}, 4{\mathrm{d}}_{\mathrm{xy}}, 3{\mathrm{d}}_{{\mathrm{z}}^2}, 3{\mathrm{d}}_{\mathrm{yz}}, 4{\mathrm{d}}_{\mathrm{yz}}, 4{\mathrm{d}}_{{\mathrm{z}}^2}$