b
The decrease of ring strain can provide a driving force strong enough to  overcompensete for the conversion of a more stable into less stable cationic  centre, the carbooxonium ion \((A)\) rearranges into the carbonium ion \((B)\) because of the release of cyclo butene strain \((2 6 \,kcal/mol)\) in the formation of  the cyclopentane (ring strain of about \(5\, cal/mol\)) cation \(B\) stablizer itself by way of another \(1,2\) rearrangement. The resulting action \((c)\) has comparebly little ring strain but is an electronically favourable carboxonium ion.