(Crystal Field Theory) When the valence d orbitals of the central metal ion are split in energy in an octahedral ligand field, which orbitals are raised least in energy?

Question

$\begin{array}{1 1}(a)\;d_{\large xy}\; and \;d_{\large x^2-y^2}\\(b)\;d_{\large xy}, d_{\large xz}\; and\; d_{\large yz}\\(c)\;d_{\large xz}\; and \;d_{\large yz}\\(d)\;d_{\large xz}, d_{\large yz}\; and \;d_z2\end{array}$