How is a cliff characterized?

A cliff is characterized primarily as a vertical or near-vertical slope that is visually represented by closely spaced contour lines on a topographic map. This portrayal indicates a significant change in elevation over a short horizontal distance, which is a fundamental aspect of a cliff's formation. Cliffs typically arise due to geological processes such as erosion caused by wind, water, or ice, leading to steep rock faces. The presence of touching contour lines emphasizes the abrupt nature of the drop-off relative to the surrounding terrain, which is not the case for features that are less steep or gradual, like those suggested in the other options.

Other choices reference man-made structures, natural landforms that do not imply a steep drop, or configurations that lack the defining vertical characteristics of a cliff. Thus, the distinctive vertical profile and the closely spaced contour lines accurately encapsulate the essence of what characterizes a cliff.