What is the primary function of teasers in a theatre setting?

Teasers serve the purpose of masking the height of the stage, which is essential in creating a cohesive visual environment for the audience. By hiding the upper areas of the stage, including the bars and rigging overhead, teasers help to eliminate distractions that might take the audience out of the performance. They contribute to maintaining the illusion of the set design and can enhance the overall aesthetics of the production by ensuring that what is visible aligns with the intended artistic vision.

In this context, while other options such as supporting lighting fixtures or covering side stage areas relate to practical functions in theatre, they do not accurately describe the primary role of teasers. Teasers specifically address the vertical aspect of stage design by controlling sightlines from the audience's perspective, which is vital for immersive storytelling in a theatrical production.