Concept:Relief rainfall happens when moist air is forced upward by high ground such as mountains or hills.Explanation:When wind carrying moist air meets a highland area, the air is pushed upward.As the air rises, it cools and condenses, forming clouds and producing rainfall.This type of rainfall is therefore most common in highland areas.Lowland areas, peneplains, and deserts are too flat or dry to cause this lifting effect.Answer:C. Highland areas