The decreasing order of nucleophilicity among the following nucleophiles is:

Generally, a stronger base is a better nucleophile in a given solvent (unless steric factors dominate).${\text{CN}}^{-}$ and ${\text{CH}}_3{\text{O}}^{-}$ are strong bases.${\text{CH}}_3{\text{COO}}^{-}$ is a weak base due to resonance.${\text{CH}}_3{\text{SO}}_3^{-}$ is the weakest base (conjugate of a sulfonic acid).The order is ${\text{CN}}^{-}>{\text{CH}}_3{\text{O}}^{-}>{\text{CH}}_3{\text{COO}}^{-}>{\text{CH}}_3{\text{SO}}_3^{-}$.