The passage never states that the Food and Drug Administration (FDA) ignores products after they enter the market. In fact, the entire fourth paragraph describes the steps taken by the FDA to regulate products once they are available for purchase. In some cases, questions of this type will contain answer choices that are directly contradictory. Here, for instance, answer choices A and B cannot be true if answer choice D is true. If there are at least two answer choices that contradict another answer choice, it is a safe bet that the contradicted answer choice cannot be correct. If you are at all uncertain about your logic, however, you should refer to the passage.