(d)
$\ ^{\ominus}CH_{2}CHO$ is the most stable carbanion since it is stabilize by resonance
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ O\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ O^{-}$
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$\ ^{-}CH_{2} - C - H \longleftrightarrow CH_{2} = C - H$