The correct option is D The particular juxtaposition of shapes in an illustration that makes one shape look as though it were behind another
Look at these lines in the first paragraph.
“By illusion I mean those contrivances of color, line, shape, and so forth that lead us to see marks on a flat surface as depicting three-dimensional objects in space”
This is a main theme inference question. The whole passage is regarding usage of illusion in art. The definition of illusion is in the above lines.
Look at the above line given in bold.
That will lead you to the correct answer (D) and not (C). C generically talks about 3D image. We need an illusion.