What are treads in the context of stage design?

In stage design, treads refer specifically to the steps that connect different levels of the stage area. These treads are integral in facilitating movement between various levels, allowing actors to traverse the stage more easily and creating dynamic visual possibilities. They enhance the functional aspects of the set by providing access to elevated platforms or areas, thereby contributing to the overall staging of a production.

The other options do not align with the definition of treads in stage design. Decorative elements on stage can enhance the visual aesthetic but do not serve the functional purpose of facilitating movement between levels. Audience seating is a separate component of theatre design, aimed at accommodating spectators rather than the performance space itself. Lighting fixtures are crucial for illuminating the stage but are not related to the concept of treads or steps in physical space. Thus, the characterization of treads as steps or levels connecting different parts of the stage accurately captures their role in set design.