What line is used to indicate locations of a section or elevation on a blueprint?

The section line is the appropriate choice for indicating the locations of a section or elevation on a blueprint because it serves a specific purpose in architectural and engineering drawings. This line is typically a dashed or broken line that marks where a section cut is made through a building or object to reveal internal details in a drawing.

When looking at a blueprint, the section line points to the exact area from which the section is derived, guiding viewers to understand which part of the design is being represented in the section or elevation view. It also aids in visualizing how different parts of a structure relate to one another.

Dimension lines are used to communicate measurements and dimensions on a plan but do not indicate section locations. Center lines are employed to define the centers of objects, which is useful in ensuring symmetry or alignment but not for indicating sections. Extension lines extend from the object to give reference points for dimensioning rather than directing to a section cut.

Thus, the section line is specifically designed for this function, clearly communicating where the internal views are represented on the blueprint.