Final answer:
The use of value to create the illusion of depth is achieved through modeling, where varying tones suggest the way light interacts with a three-dimensional object, giving it form and depth in a two-dimensional representation.
Step-by-step explanation:
The use of value to create the illusion of depth is known as modeling. Modeling involves varying the tonality from light to dark to simulate light falling on a three-dimensional object in a two-dimensional space. This is different from other techniques such as chiaroscuro, which creates a sense of depth or volume through the contrast of light and dark; sfumato, which involves the subtle blending of colors and tones to give a three-dimensional feel; and foreshortening, which is the compression of lines in a drawing to make it appear as if an object is receding into the distance.
Through careful adjustments of value, artists like Raphael in 'La Donna Velata' used shading—the application of darker colors to suggest shadows—to convey the illusion that objects in a painting have mass and exist in a three-dimensional space.
Therefore, the correct answer is b. modeling.