Which of the following is the most unstable resonating structure?

Which one of the following compounds does not exhibit resonance?

Arrange the following in the decreasing order of stability:
$I. CH_2=CH-CHO$
$II. ^+CH_2-CH=CH-O^-$
$III. ^-CH_2-CH=CH-O^+$

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 $:$

Compare the ease of carbon-carbon bond rotation across $A, B,$ and $C$.

In which of the following is the first resonating structure less stable compared to the second one?