Correct answer: (a) d_x²-y², d_z²

Explanation:

Only those d orbitals whose lobes are directed along X, Y and Z directions hybridise with s and p orbitals. In other three, d orbitals namely d_xy, d_yz and d_xz, the lobes are at an angle of 45° from both axis, hence the extent of their overlap with s and p orbitals is much lesser than d_x²-y² and d_z² orbitals.