Which line type helps illustrate where a dimension ends?

The correct choice is the extension line, which is essential in welding prints and technical drawings to indicate where a dimension begins and ends. Extension lines are thin lines that extend from the edges of the feature being measured to the dimension line, clearly specifying the boundaries of the measurement. This ensures that anyone reading the print can understand precisely which part of the drawing the dimension refers to.

Dimension lines are used to show the actual measurement values, while break lines serve to indicate where a part does not continue, usually to save space or to depict a cut. Hidden lines represent features of an object that are not directly visible in the view being represented, such as internal edges or contours, but they do not indicate the endpoints of dimensions. In technical drawings, the correct use and understanding of these line types are crucial for accurate communication and interpretation of the design.