The correct answer is A. She should paraphrase it, because its exact wording is not creative or unique.
In research papers, quotations should be used very sparingly, and only used when a source contains a creative or unique point that can add a nice touch if added to a research paper. The sentence, "Romeo and Juliet seems to be the most popular of Shakespeare's plays" is neither creative nor unique, which is why Catie is better off paraphrasing it in her report rather than directly quoting it.
