Which one of the following

$\mathrm{T}_{\mathrm{f}}-\mathrm{T}_{\mathrm{f}}^{\prime}=\mathrm{i} \mathrm{K}_{\mathrm{f}} \cdot \mathrm{m}$

For minimum $\mathrm{T}_{\mathrm{f}}^{\prime}$

'i' should be maximum.

$\begin{array}{ll}\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3} & \mathrm{i}=5 \\ \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} & \mathrm{i}=1 \\ \mathrm{KI} & \mathrm{i}=2 \\ \mathrm{~K}_{2} \mathrm{SO}_{4} & \mathrm{i}=3\end{array}$