What lines are primarily used to represent the edges of an object in a sketch?

Visible lines are utilized in sketches to represent the edges of an object clearly and distinctly. These lines are typically dark, solid lines that define the outlines and significant features of the object being drawn. Their primary purpose is to make the shape and contours of the object easily recognizable, allowing anyone reviewing the sketch to understand its form and dimensions without ambiguity.

In contrast, construction lines are lighter and often used as guides during the sketching process to help place objects accurately but do not appear in the final drawing. Section lines indicate areas that have been cut through an object for a sectional view, often used in technical and engineering drawings to show internal features. Dimension lines, on the other hand, are used to provide measurements and specifications about the size of the object seen in the sketch. While all these lines serve specific functions in technical drawing, visible lines are the key representation of the edges of an object, making the correct choice evident.