Which of the following is a design element?

The correct answer, which identifies a design element, is form. In design, 'form' refers to the shape and structure of an object or an element within a composition. It encompasses both the three-dimensional aspects and the perception of depth, contributing significantly to how we interpret and interact with a design. Form can be geometric or organic, and it influences the visual weight and balance in a design.

In contrast, while proportion, repetition, and movement/rhythm are important aspects of design, they fall under design principles rather than elements. Proportion relates to the size relationships between different parts of a design; repetition involves the use of similar shapes, colors, or patterns throughout a design to create cohesion; and movement/rhythm describes the way in which the viewer's eye is guided through a composition. These principles aid in organizing the elements within a design but do not define the elemental aspects like form does.