Which of the following resonance structures is the least stable?

Which one of the following compounds does not exhibit resonance?

Given below are two statements.
Statement $I :$ The dipole moment of $CH_3-CH=C(CH_3)-CH=O$ is greater than $CH_3-CH_2-CH_2-CH=O$.
Statement $II :$ $C_1-C_2$ bond length of $CH_3-CH=CH-CH=O$ is greater than $C_1-C_2$ bond length of $CH_3-CH_2-CH_2-CH=O$.
In the light of the above statements,choose the correct answer from the options given below $:$

Identify the compound in which steric inhibition of resonance is present.

Correct statements for the given reaction are :
$A$. Compound '$B$' is aromatic
$B$. The completion of above reaction is very slow
$C$. '$A$' shows tautomerism
$D$. The bond lengths $C-C$ in compound $B$ are found to be same
Choose the correct answer from the options given below :

Select the correct statement for the given structures of anilinium ion: