$$
\mathrm{CH}_3 \mathrm{Br}+\mathrm{Nu}^{-} \longrightarrow \mathrm{CH}_3-\mathrm{Nu}+\mathrm{Br}^{-}
$$
The decreasing order of the rate of the above reaction with nucleophiles $\left(\mathrm{Nu}^{-}\right) \mathrm{A}$ to $\mathrm{D}$ is $\left[\mathrm{Nu}^{-}=(\mathrm{A}) \mathrm{PhO}^{-}\right.$, (B) $\mathrm{AcO}^{-}$, (C) $\mathrm{HO}^{-}$, (D) $\left.\mathrm{CH}_3 \mathrm{O}^{-}\right]$