It is useful because you see everybody's perspective, you compare how one critic saw it, with the way someone else saw it. You get different conclusions, and you bring your own thoughts into this discussion of intellectuals. The correct answer should be a) <span>It allows you to compare information and make sure you're presenting the most correct and useful data.</span>
C is the right one. Unlike quotations or paraphrased ideas, information that's considered "common knowledge" doesn't need to be cited. "Common knowledge" is information that's considered widely known or easily verified.
