Which line type typically denotes visible edges of the part?

Object lines are the correct choice for denoting visible edges of a part in technical drawings and blueprints. They are represented as solid, thick lines and serve to define the shape and outline of an object clearly. This allows anyone viewing the drawing to easily identify the boundaries and prominent features of the part being depicted.

In contrast, hidden lines are used to indicate edges that are not visible from the current viewpoint and are typically represented by dashed lines. Center lines are used to denote axes of symmetry or the center points of features, and they are often drawn as long and short alternating dashes. Dimension lines provide measurements of the part's features and are also distinct in appearance, generally comprising a thin line extending from which dimensions are noted. Each of these other line types serves a specific purpose that differs from the function of object lines in conveying the visible edges of a part.