What is a drawing of the set from above, indicating what is on stage and the layout of entrances and exits?

A ground plan is a crucial tool in stage production that provides a bird's-eye view of the set layout. It details the arrangement of set pieces, props, and the locations of entrances and exits, allowing the production team to visualize how the space will be utilized during a performance. This schematic representation is essential for blocking scenes and coordinating movement on stage, ensuring that actors can navigate the space effectively while adhering to the director's vision.

In contrast, a key typically refers to a symbol key that explains the elements depicted in a visual representation but does not provide the layout itself. A set prop is an item used on stage for a performance but does not encompass the broader layout of the set. Rostra refers to platforms or raised sections of the stage but does not relate specifically to the overall floor plan. Therefore, the ground plan stands out as the accurate choice for indicating the comprehensive layout and spatial arrangements of the performance area.