(B) is wrong because the author does not say that the front-to-back explanation of what mirrors do is successful, it's only successful TO A POINT (lines 27-28). In addition, this success isn't because it rejects ANY consideration of mental constructs. Indeed, the reason the explanation is appealing is because we are accustomed to dealing with mental constructs and not with primary sense perceptions.
(E), on the other hand, encapsulates the author's point. Why is the explanation only successful to a point? Because it doesn't consider what happens when we look into mirrors, which is one of the two important elements the author brings up at the end. Hope this helps!