The author suggests that which of the following constitutes a potential disadvantage of using latent heat for energy storage? A. The circumstances under which phase transitions occur would limit the versatility of latent heat as a storage method. B. The supply of substances that possess the properties that are needed in a medium for latent heat storage is dwindling. C. The properties that are needed in a medium for latent heat storage are found in substances that have other, undesirable properties.