Final answer:
Caves and sinkholes are the geological structures made from Karst topography, which occurs due to the dissolution of soluble rocks such as limestone.
Step-by-step explanation:
The geological structures made from Karst are caves and sinkholes. Karst topography is characterized by the dissolution of soluble rocks such as limestone, leading to the creation of various features.
The process of water eroding the limestone is responsible for forming vast networks of caves, as well as surface depressions known as sinkholes. Notably, this process can also lead to the formation of other structures like stupendous stalactites and stalagmites within caves, due to the deposition of calcium carbonate from dripping water within the cave system.
Volcanoes, mountain ranges, and sand dunes are not typically associated with Karst topography. These features have different geological formation processes, such as the movement of tectonic plates for mountain ranges, and wind-blown sediment accumulation for sand dunes. Instead, the most distinct features of Karst landscapes include not only caves and sinkholes but also disappearing streams, subterranean rivers, and irregular, hilly terrain.