We're looking for a flaw in the reasoning that the argument makes. The author sets out two beliefs of the critics: (1) they believe that poems can never be accurately paraphrased, and (2) their own paraphrases of certain poems are accurate ones. The author then concludes that (1) is false, and that it must be true that poems can be accurately paraphrase. But the author doesn't give a reason for concluding that (1) is false; (2) could just as easily be false. Perhaps the critics' paraphrases of those poems are inaccurate, and (1) is still true. Since the argument doesn't give us a reason to favor one interpretation over the other, and it apparently arbitrarily picks one, it's a valid criticism to point this out, and this is what (D) does. Hope this helps!