Final answer:
Freezing point depression is the phenomenon where the freezing point of a solvent decreases when a solute (such as salt or sugar) is added to it. The solution with the lowest freezing point would be the one with the highest concentration of solute.
Step-by-step explanation:
The question is asking about the freezing point depression in a solution. Freezing point depression is the phenomenon where the freezing point of a solvent decreases when a solute (such as salt or sugar) is added to it. The solution with the lowest freezing point would be the one with the highest concentration of solute. In this case, the solution with 0.2 m NaCl has the lowest freezing point, followed by 0.3 m acetic acid, 0.1 m CaCl₂, and 0.2 m sucrose with the highest freezing point.