# The correct stability order for the following species is

$(a)\;II > IV > I > III \\ (b)\;I > II > III > IV \\ (c)\;II > I > IV > III \\ (d)\;I > III > II > IV$

Resonance stabilized having six hyper conjugating H-atom
Resonance stabilised having three hyper conjugating H-atom
five hyper conjugating H-atom
Two hyper conjugating H-atom.
Stability of the following species depends upon the no of $\alpha$ hydrogen, higher will be the stability of the compound.
So $I > III > II > IV$
Hence d is the correct answer.