Answer:
B. a mound of sand piled up by the wind.
Step-by-step explanation:
It is option B because a dune is a natural feature formed by the wind blowing sand particles and piling them up in a specific area. The wind can shape the dune and cause it to grow taller, sometimes reaching heights of 300 meters or more. Dunes are not caused by the wind blowing sand away, as stated in option A, nor are they found in wet and rainy areas, as stated in option D, they are typically found in desert regions or along coastlines. It is not a cave as stated in option C.