What type of dune is typically formed in coastal areas?

The correct answer is sand dune. Sand dunes are typically formed in coastal areas due to the accumulation of loose sand that is blown by the wind. In coastal environments, the availability of sand, such as from beaches or coastal deposits, allows for the formation of these dunes. The wind plays a significant role in shaping these features, moving the sand particles and causing them to accumulate into mounds or ridges.

Other types of dunes, such as rock dunes or clay dunes, are not commonly associated with coastal environments. Rock dunes generally consist of rock formations that are shaped by geological processes, and clay dunes are associated with fine sediment in different landforms, typically away from sandy coastal regions. Ridge dunes could also form but are more specific in their structure and not the primary type found in coastal zones. Therefore, sand dunes are recognized as the characteristic dune type in such settings due to their composition and formation process.