What would happen when a substance changes from one phase to another? A. The substance loses or gains heat. B. The average kinetic energy of the substance changes. C. The temperature of the substance changes. D. The molecular motion of the substance changes.

I think the correct answer from the choices listed above is option B. When a substance changes from one phase to another, the average kinetic energy of the substance changes since the molecules movements are changed as well. Hope this answers the question. Have a nice day.