Correct Answer - b
The decrease of ring can provide a driving force strong enough to overcompensete for the conversion of amore stable into less stable cationic, centre the carbooxonium ion (A) rarranges into the carbonium (B) beacuse of the release of cyclo butene strain (26 kcal/mol) in the formation of the cyclopentene (ring strain of about 5 cal/mol) cation B stablizer itself by way of another 1,2 rerrangement. The resulting action (c) has comparebly little ring strain bur ia an electronically favourable carboxonium ion.
