In what kind of topography is a 'sink' typically formed?

A sink is typically formed in karst topography due to the dissolution of soluble rocks, such as limestone, by water. This geological process leads to the development of unique landforms that include sinkholes, which are depressions or holes in the ground. In karst regions, the underlying stone is eroded over time, creating a network of underground drainage systems and cavities. When the roof of one of these cavities collapses, a sinkhole is formed, leading to a noticeable change in the surface landscape.

In contrast, mountainous terrain often consists of solid rock formations and steep slopes where the conditions for sinkhole formation are not as prevalent. Flat plains do not typically have the geological conditions conducive for the cavitation that leads to sinkholes, as there is often a lack of soluble rock. Similarly, desert landscapes, while they may experience erosion, usually do not have the chemical processes occurring beneath the surface that facilitate the creation of sinks. Thus, karst topography is the most suitable answer, as it fundamentally allows for the processes that create sinks.