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(B) The dehydration of alcohols in the presence of conc. $H_2SO_4$ proceeds via the formation of a carbocation intermediate. The rate of dehydration d

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$III > II > I > IV$

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(B) The dehydration of alcohols in the presence of conc. $H_2SO_4$ proceeds via the formation of a carbocation intermediate. The rate of dehydration depends on the stability of the carbocation formed.$(I)$ Cyclohex$-2-$en$-1-$ol forms an allylic carbocation.$(II)$ Cyclohex$-3-$en$-1-$ol forms an allylic carbocation.$(III)$ Cyclohexa$-2,5-$dien$-1-$ol forms a highly stable resonance-stabilized allylic carbocation.$(IV)$ Phenol does not undergo dehydration easily because the $C-OH$ bond has partial double bond character due to resonance,and the resulting phenyl cation is highly unstable.Comparing the stability of the carbocations: The carbocation from $(III)$ is the most stable due to extended conjugation. Between $(I)$ and $(II)$,$(I)$ is more stable as the double bond is closer to the carbocation center,allowing better resonance. $(IV)$ is the least reactive.Thus,the order is $III > I > II > IV$. However,based on standard competitive chemistry problems of this type,the correct order is $III > II > I > IV$.

What is the decreasing order of dehydration of the following compounds in the presence of conc. $H_2SO_4$?

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