The correct decreasing order of vapour phase dipole moments of $CH_3-x$ is as follows

Question

\begin{array}{1 1}(a) CH_3-F > CH_3-Cl > CH_3-Br > CH_3I \\(b) CH_3I > CH_3-Br > CH_3-Cl > CH_3-F\\ (c) CH_3-Cl > CH_3-F > CH_3-Br > CH_3I\\( d) CH_3-Cl > CH_3 -Br > CH_3I > CH_3-F\end{array}