I came across this question:
Which is the most stable resonating structure of p-nitrosobenzene among the following?
I have been taught about the priorities for resonance structure stability as follows:
Complete octet $\rightarrow$ more stable
Uncharged $\rightarrow$ more stable
Lower formal charge $\rightarrow$ more stable
Less separation between opposite charges $\rightarrow$ more stable
Negative charge near more electronegative atoms and positive charge near less electronegative atoms $\rightarrow$ more stable
So according to the above rules, (b) and (c) are the among the most stable. Bu then applying rule #4 above, (b) should be more stable, because here each positive charge is in vicinity of negative charge.
However the answer given is (c). Why is this?