Which of the following molecules has the maximum dipole moment?

1. ${\text{CO}}_2$ and ${\text{CH}}_4$: Symmetrical molecules, $\mu =0$.2. ${\text{NH}}_3$ and ${\text{NF}}_3$: Both are pyramidal.In ${\text{NH}}_3$, the bond dipoles and the lone pair dipole are in the same direction, adding up to a high value.In ${\text{NF}}_3$, the electronegative Fluorine pulls electron density away from Nitrogen, opposing the lone pair dipole. This results in a much lower net dipole moment.