An untitled map with labeled points A through point C. Point A is located close to where a river meets a larger body of water. Point B is located inland away from any bodies of water. Point C is located near a mountain range.

Use the map to choose the letter from the drop-down menu that answers the question.

Which area is a desert covered in sand dunes?

Which area receives rains that bring water to river valleys?

Which area is a coastal region with marshes?

Since we do not have access to the map, we cannot accurately choose a letter from a drop-down menu. To answer the questions, we can make educated guesses based on the given information:

- The area with sand dunes is likely to be a desert, particularly if it is located away from bodies of water. Therefore, it is unlikely to be point A (close to where a river meets a larger body of water) or point B (inland away from any bodies of water). It could be point C if it is near a mountain range, as deserts often form in rain shadows behind mountains.

- The area that receives rains and brings water to river valleys is likely to be closer to a larger body of water, such as point A. Bodies of water are often the source of moisture for rainfall.

- The coastal region with marshes is likely to be close to where a river meets a larger body of water, as these areas often have brackish water or estuaries that support the formation of marshes. Therefore, point A is the most likely option for a coastal region with marshes.

Again, without access to the map, these answers are educated guesses based on the provided information.