Arrange the carbanions, $({\text{CH}}_3{)}_3{\text{C}}^{-}$, ${\text{CCl}}_3^{-}$, $({\text{CH}}_3{)}_2{\text{CH}}^{-}$, ${\text{C}}_6{\text{H}}_5{\text{CH}}_2^{-}$, in order of their decreasing stability:

Carbanion stability is increased by electron-withdrawing groups ($-I$, $-M$) and resonance, and decreased by electron-releasing groups ($+I$).${\text{CCl}}_3^{-}$: Highly stabilized by the strong $-I$ effect of three $Cl$ atoms and $d$ -orbital resonance.${\text{C}}_6{\text{H}}_5{\text{CH}}_2^{-}$: Stabilized by resonance with the benzene ring.$({\text{CH}}_3{)}_2{\text{CH}}^{-}$: Secondary carbanion, destabilized by two methyl groups ($+I$).$({\text{CH}}_3{)}_3{\text{C}}^{-}$: Tertiary carbanion, most destabilized by three methyl groups ($+I$).Order: ${\text{CCl}}_3^{-}>{\text{C}}_6{\text{H}}_5{\text{CH}}_2^{-}>({\text{CH}}_3{)}_2{\text{CH}}^{-}>({\text{CH}}_3{)}_3{\text{C}}^{-}$