What defines 'shape' in the context of art?

In the context of art, 'shape' specifically refers to an enclosed space that is defined by lines and colors. Shapes can be geometric, like squares and circles, or organic, resembling natural forms. They play a crucial role in artwork by creating a sense of structure and balance, allowing for differentiation between elements within a composition. Artists manipulate shapes to guide the viewer's eye and create relationships between different components of the artwork.

While the other options touch on relevant aspects of art and theater—such as techniques of painting or the emotional expression of characters—they do not define 'shape' itself. The layering of colors focuses on techniques of application rather than the definition of shape, arrangement on stage pertains more to composition in performance rather than the visual aspect in painting, and emotional expression relates to character portrayal, which is less about the spatial or visual concept that 'shape' embodies in art.