Final answer:
The principle of design that is important in Ruben's Prometheus Bound is composition.
Step-by-step explanation:
The principle of design that is important in Ruben's Prometheus Bound is composition. Composition refers to the arrangement and organization of the elements in a work of art to create a visually pleasing and impactful result.
In Prometheus Bound, Ruben carefully arranges the elements of design, such as lines, color, and figures, to create a sense of movement, rhythm, and a strong center of interest. This composition draws the viewer into the artwork and holds their attention.