The signs (symmetry) of the overlapping lobes must match in order to produce a bonding MO (with a concentration of electron density between the nuclei). The signals of the overlapping lobes must also differ for antibonding MOs.

Any stability in the combination above caused by the overlap of + with + is counterbalanced by an equivalent amount of overlap of + with. Nonbonding is the word used to describe a situation when there is no general shift of energy. The same is true for the combination of ${\mathrm{p}}_{\mathrm{x}}$ and ${\mathrm{p}}_{\mathrm{y}}$ since they are perpendicular to one another.

Hence, the option D is correct.