Which of the structures shown are enolates that can be formed from the ketone shown by removing a proton with a suitable base? Select all that apply.

The ketone shown is 1-cyclopentylpropan-1-one with two alpha carbons: the CH${}_2$ of the ethyl group and the ring CH. Removal of a proton from either gives a resonance-stabilised enolate, $\mathrm{CH}{}_3\mathrm{CH}=\mathrm{C}(\mathrm{O}{}^{-}){}^{-}$cyclopentyl or $\mathrm{CH}{}_3\mathrm{CH}{}_2\mathrm{C}(\mathrm{O}{}^{-})=$cyclopentylidene. The structures with the carbanion on the terminal CH${}_3$ or at a ring carbon beta to the carbonyl are not conjugated with C=O, so they are not enolates.