What aspect of visual art is primarily concerned with light and shadow?

The aspect of visual art that is primarily concerned with light and shadow is contrast. Contrast refers to the degree of difference between light and dark areas in a work of art. It plays a crucial role in creating depth, dimension, and volume, as it helps to define shapes and forms through the interplay of light and shadow. Artists use contrast to highlight important elements of their composition and to evoke different moods, guiding the viewer's eye to focal points within the artwork.

Texture refers to the surface quality of an artwork, whether it's smooth, rough, soft, or hard, but it does not directly relate to the manipulation of light and shadow. Composition involves the arrangement of elements within a piece, focusing on how these elements interact with one another, while line pertains to the marks made on a surface, which can help define shapes but does not inherently involve the aspects of light and shadow that contrast emphasizes. Therefore, the correct answer highlights the specific relationship between light and dark in art.