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

For ${\text{S}}_{\text{N}}2$ reactions of methyl halides, the rate depends on the nucleophilicity of the incoming group. Nucleophilicity generally follows basicity when comparing atoms in the same row.${\text{CH}}_3{\text{O}}^{-}$ (D) is more basic and a better nucleophile than ${\text{HO}}^{-}$ (C) due to the $+I$ effect of the methyl group.${\text{HO}}^{-}$ (C) is more basic than ${\text{PhO}}^{-}$ (A) because the lone pair on the phenoxide oxygen is delocalized into the benzene ring.${\text{AcO}}^{-}$ (B) is the least basic because the charge is delocalized over two oxygen atoms via resonance.Decreasing order: D > C > A > B.