Depression in freezing point is a colligative property, which depends on the number of solute particles present in the solution. For solutions of the same molality, the depression in freezing point is directly proportional to the van't Hoff factor ($i$), since $\Delta T_f = i \times K_f \times m$. Assuming complete dissociation for strong electrolytes, the van't Hoff factors are:

1. $\text{KCl} \rightleftharpoons \text{K}^+ + \text{Cl}^-$ ($i = 2$)
2. $\text{C}_6\text{H}_{12}\text{O}_6$ (Glucose is a non-electrolyte, so $i = 1$)
3. $\text{Al}_2(\text{SO}_4)_3 \rightleftharpoons 2\text{Al}^{3+} + 3\text{SO}_4^{2-}$ ($i = 5$)
4. $\text{K}_2\text{SO}_4 \rightleftharpoons 2\text{K}^+ + \text{SO}_4^{2-}$ ($i = 3$)

Since $\text{Al}_2(\text{SO}_4)_3$ yields the maximum number of particles in solution ($i=5$), it will exhibit the largest freezing point depression.