Which line is used to show alternate positions of an object without interfering with the main drawing?

The correct answer is the phantom line, which is specifically designed to represent alternate positions of an object in a drawing. This type of line is typically depicted as a series of long dashes and short dashes. Its primary purpose is to help convey multiple positions or configurations of an object, without causing distraction or confusion in the main view of the drawing. The use of phantom lines allows engineers and designers to illustrate functional relationships between various components clearly and effectively.

In contrast, hidden lines are used to show edges or boundaries that are not visible from the current viewpoint; they do not communicate alternate positions. Center lines are primarily utilized to indicate the axes of symmetry or to mark the center of circles and arcs. Construction lines serve as guides for creating the primary geometric forms in a drawing but are not used for showing alternate positions of an object. Hence, the phantom line is the most appropriate choice for this purpose.