Answer: Either B. The metallic bonds become weaker allowing the aluminum to freeze. or D. Freezing is an exothermic process
Explanation: As the aluminum cools, thermal energy leaves it. If enough energy is removed, the aluminum will freeze. Freezing is a process that is the opposite of melting—liquid changes to solid. The temperature at which matter changes from the liquid state to the solid state is its freezing point.
Furthermore, the aluminium would expand in volume as it becomes liquid. During freezing, a similar process would occur in which the top surface would initially freeze. This results in shrinkage and the aluminium detaching itself from the walls of the steel crucibles.