Concept:Wind action is strongest where dry, loose particles are exposed and not protected by vegetation.
Explanation:In arid regions, vegetation cover is sparse or absent.
So the surface consists of loose, dry materials that wind can easily lift and transport.
Humid regions usually have dense vegetation and moist soil, which bind the soil together.
This makes it harder for wind to erode or carry particles in humid areas.
Therefore, the key factor is loose surface materials combined with the absence of vegetation cover.
This matches option C.
Answer:C. Loose surface materials and the absence of vegetation cover.