When a Necker cube is made by using illusory contours, we find that ______.
the illusory contours help to disambiguate the cube
the illusory contours are not apparent inside the cube
two 3D interpretations are still apparent even when the cube is made using illusory contours
more than two 3D interpretations become simultaneously visible when the cube is made using illusory contours
the edge of the cube is incompatible with a 3D interpretation
