The effect that makes $2,3-$dimethyl$-2-$butene more stable than $2-$butene is

What is the electromeric effect?

Which of the following statements is $NOT$ correct?

Given below are two statements:
Statement $I$: On the basis of inductive effect, the order of stability of alkyl carbanions is $CH_3^- > CH_3CH_2^- > (CH_3)_2CH^- > (CH_3)_3C^-$.
Statement $II$: Allyl and benzyl carbanions are more stabilised by inductive effect and not by resonance effect.

Classify the following groups as electron-withdrawing ($-I$ effect) or electron-donating ($+I$ effect) inductive effect groups: $-CH_3, -Cl, -NO_2, -(CH_3)_3C, -OC_6H_5, -C_6H_5, -OH, -NH_2, -CH_2CH_3$.

The decreasing order of $-I$ (inductive) effect power for the given groups is:
$A. -CN$
$B. -NO_2$
$C. -NH_2$
$D. -F$