Correct Answer - D
`CO_2` and `CH_4` have zero dipole moment as these are symmetrical in nature. Between `NH_3` and `NF_3` , `NF_3` has greater dipole moment though in `NH_3` and `NF_3` both, N possesses one lone pair of electrons.
This is because in case of `NH_3`, the net N-H bond dipole is in the same direction as the direction of dipole of lone pair but in case of `NF_3`, the direction of net bond dipole of three -N-F bonds is opposite than that of the dipole of the then lone pair.
