In Tertiary alcohols (3^o) the hydroxyl group is easily substituted by the halide group due to greater stability of the carbocation in comparison to primary carbocation and secondary carbocationformed during the reaction.

The greater stability is due to the more inductively donating alkyl groups.The hyperconjugation effect can also be invoked to explain the relative stabilities of primary, secondary, and tertiary carbocations.

Thus, the correct order of the reaction is 3^o>2^o>1^o in increasing order.

Thus, all other options are wrong.