To define the picture plane, the two-dimensional artist must establish
a. the borders of the artwork.
b. specific atmospheric perspective.
c. a figure-ground ambiguity.
d. a vanishing point/horizon.

The correct answer among the choices given is option D. To define the picture plane, the two-dimensional artist must establish a vanishing point/horizon.  linear perspective is a design where parallel lines converge into a point on an imaginary line or the vanishing point creating an illusion of depth on a two-dimensional surface.