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

The order acid-strength of the conjugate acids of the given bases is  ${\mathrm{CH}}_3\mathrm{OH}<{\mathrm{H}}_2\mathrm{O}<\mathrm{PhOH}<\mathrm{AcOH}$ The base-strength of the given bases will be

${\underset{\mathrm{D}}{{\mathrm{CH}}_3\mathrm{O}}}^{-}>\underset{\mathrm{C}}{{\mathrm{OH}}^{-}}>\underset{\mathrm{A}}{{\mathrm{PhO}}^{-}}>\underset{\mathrm{B}}{{\mathrm{AcO}}^{-}}$The stronger the base, stronger the nucleophile, greater the rate of nucleophilic displacement.