What are M.C.Escher's paintings,which often include impossible staircases and other structures,viewed as examples of

A)  perceptual ambiguity 
B)  pointillism 
C)  cubism 
D)  Gestalt continuity

Perceptual Ambiguity

A situation in which a visual stimulus lacks a clear interpretation due to conflicting perceptions or because it can be seen in more than one way.

Pointillism

An art technique where small, distinct dots of color are applied in patterns to form an image, associated with post-Impressionist painters.

Cubism

An early 20th-century art movement marked by the use of geometric shapes and a viewpoint that represents subjects from multiple perspectives.