Concept:Sublimation is the direct change of a substance from solid to gas without becoming a liquid.Explanation:When a solid is heated and disappears completely as a gas, it has not melted first.This direct solid-to-gas change is called sublimation.Examples include iodine and dry ice (solid CO2).Crystallization, distillation, and evaporation all involve the liquid state, so they do not match this description.Answer:A. Sublimation