(D) is correct because if a painter can suppress details about a sitter at odds with an imaginary persona, and thus make the sitter resemble the imaginary persona, the painting will not be as realistic as a photograph might be, making it easier for the viewer to suspend disbelief.
(B), however, is incorrect because even if paintings can depict obviously impossible situations, these kinds of situations in general are harder to suspend our disbelief for. They are, after all, obviously impossible. If a painter painted a human with ten arms, we wouldn't necessarily suspend our disbelief with regards to that painting. Hope this helps.