(i) Number of $\pi$ bonds $\alpha$ Resonance energy $\alpha$ stability
(ii) Contributing structures should be such that negative charge resides on an electronegative element and positive charge resides o am electro positive element.
(iii) In contributing structures , like charges should not reside on atoms close to each other and unlike charges should be widely separated .
So, $I > III > II >IV$
Hence b is the correct answer