Final answer:
Color, line, and shape are the main elements of art used to create the illusion of form, volume, and three-dimensional space on a two-dimensional plane.
Step-by-step explanation:
The elements of art that are used to create the illusion of form, such as in Op Art, primarily include color, line, and shape. Artists can manipulate these elements to create a sense of volume and three-dimensional space within a two-dimensional medium. For instance, the use of gradients in color and the strategic placement of lines can give the impression of curvature and depth, much like Anuszkiewicz did in his pieces where patterns and parallel colored lines create a sense of volume and space. Moreover, the arrangement of shapes in particular patterns can also contribute to the illusionary perception of a form that extends beyond the flat surface.