Victor Vasarely's Approach Is Known as Kinetic Art

Victor Vasarely's approach is known as Kinetic Art. How does he use optical illusions in his work?

A) He makes it seem as if there are three-dimensional images popping out of a background of arbitrary features.
B) He hides images of nudes within advertising images.
C) He makes it appear as if geometric shapes are moving or changing shape.
D) He creates a complex image from tiny points of paint or charcoal.