Please explain

23. Which of the following represents the correct order of stability of the given carbocations ?

(1)  III > I > II                                                                 (2)  I > III > II

(3)  III > II > I                                                                 (4) II > III > 1

Dear student,

The III sturcture is aromatic since it follows (4n+2)$\pi$ electron system hence it is most stable.
The II structure possess anti aromatic behaviour due to which it is very unstable whereas the I structure is resonance stabilized and also possess aromatic behaviour in the ring hence the order should be

III>I>II

Hope this helps,

Regards