Arrange the following carbanions in order of their decreasing stability

A) $C{H}_3-C\equiv C^{\Theta }$   B) $H-C\equiv C^{\Theta }$   C) $C{H}_3-C{H}_2^{\Theta }$

+I effect decreases the stability of carbanion. Since $C{H}_3$ group has +I effect, therefore it intensifies the negative charge and hence destabilizes (A) relative to (B) SP hybridized carbanion is more stabilized than $S{P}^3$ . Hence $HC\equiv C^{\Theta }>C{H}_3-C\equiv C^{\Theta }>C{H}_3-C{H}_2^{\Theta }$, so $B>A>C$.