On a topographical drawing, a ______________ line shows the elevation in feet above sea level.

The correct answer is "contour" line. Contour lines are a fundamental element on topographical drawings and maps. They represent lines of equal elevation, allowing the viewer to understand the three-dimensional shape of the terrain in a two-dimensional format. Each contour line connects points that are at the same elevation above sea level, providing crucial information about the gradient and slope of the land.

By interpreting these lines, one can visualize hills, valleys, and other landforms, which are critical for various applications in construction, land development, and outdoor activities. The spacing of contour lines also indicates the steepness of the terrain; closer lines suggest a steeper slope, while wider spaces indicate a gentler slope. This makes contour lines essential for planners and builders who need to assess land for potential projects.

In contrast, vertical lines do not convey elevation but can represent other dimensions or elements on a drawing. Horizontal lines typically indicate flat surfaces or relationships in plans but do not provide elevation information. Lastly, benchmarks refer to specific points of reference used for elevation measurements but are not depicted in the same manner as contour lines on a map.