The delocalization of $\sigma$ electrons of $C-H$ bond of an alkyl group with the $\pi$ electrons of benzene is observed in

The most stable carbocation among the following is:

Select the correct set of substituents for the existence of $-M$ and negative inductive $(-I)$ effects.

Steric inhibition of resonance takes place in

The decreasing order of acidic strengths of the following compounds is:

Given below are two statements:
Statement $I$: In $O_2N-C_6H_4-CH^+-C_6H_4-OCH_3$, the carbocation is stabilised by $+R$ effect of $-OCH_3$ group.
Statement $II$: In $O_2N-C_6H_4-CH^--C_6H_4-OCH_3$, the carbanion is stabilised by $-R$ effect of $-NO_2$ group.
In the light of the above statements, choose the correct answer from the options given below: