We can see evidence for (C) by looking at line 38, where we see a "Note, for example." This tells us that we're getting a further explanation of something mentioned previously, and the sentence right before tells us that mirrors make 2D surfaces look 3D. (C) encapsulates this idea perfectly.
(D) is incorrect because it creates a link not made in the passage. It is true that we typically deal directly with mental constructs, not perceptions, but our tendency to not focus our eyes on mirrors does not illustrate this. Hope this helps!
