Which of the following best describes a depression on a map?

A depression on a map refers to a low area that is surrounded by higher ground, which is accurately captured by the correct choice. This geographical feature is typically indicated by contour lines that form concentric circles, where the innermost circle represents the lowest point and the outer circles denote the higher elevations surrounding it.

Understanding this allows one to interpret topographical maps better, as depressions can indicate various landforms such as basins or valleys. Recognizing the relationship between elevations and depressions is essential in geology, environmental studies, and land use planning. The other options do not accurately describe a depression; a raised area describes an elevation, a flat region signifies uniform land with no significant changes in elevation, and a river bank involves the edges of a river which can be either level or elevated, but does not denote a low area surrounded by higher ground.