Final answer:
Ice used for cooling food should be made from liquid water because ice made from other substances would not be as effective in maintaining a low temperature.
Step-by-step explanation:
Ice used for cooling food should be made from liquid water. When water freezes, it expands in volume and becomes less dense than liquid water. This property allows ice to float on top of liquid water. If ice made from other substances, such as ethanol, were used for cooling food, it would not be as effective in maintaining a low temperature. Therefore, it is important to use liquid water to make ice for cooling food.