The correct order of the rate of reaction of the following reactants with nucleophile by \( \mathrm{S_{N}1} \) mechanism is: (Given: Structures I and II are rigid)
\( \text{I} < \text{II} < \text{III} < \text{IV} \)
\( \text{II} < \text{I} < \text{III} < \text{IV} \)
\( \text{IV} < \text{III} < \text{II} < \text{I} \)
\( \text{III} < \text{I} < \text{II} < \text{IV} \)
