The compound shown is treated with a base and loses one proton from carbon. Which carbanion shown is the most stable?

The compound shown is ethyl acetoacetate. Deprotonation of the central CH${}_2$ gives a carbanion flanked by two carbonyl groups, which delocalises the charge onto both oxygens. The CH${}_3$ carbanion is stabilised by only one carbonyl, and the carbanions on the ethyl group are not conjugated with any carbonyl.