A French curve is best described as?

A French curve is accurately described as a template used to draw smooth curves with various radii. It is a tool often made from plastic or flexible material, featuring a variety of curves that can assist in creating precise, continuous lines in drafting and design work. This makes it particularly useful for technical drawings, such as those encountered in civil engineering and surveying. By providing an array of curve shapes, the French curve allows users to smoothly connect points that require a gentle transition, which is crucial in many types of graphical representations.

In contrast, the other options refer to different categories of tools. Surveying instruments include items such as theodolites and total stations, which are meant for measuring angles and distances in land surveying. Software tools focus on digital calculations and computer-aided design, tasked with calculating angles and providing graphing capabilities rather than manual drawing. Measuring devices are specifically for distances, which would not encompass the smooth curve-drawing function that a French curve serves.