B contradicts passage

Hello @amber-damerow, I'll explain why B supports the argument. The author presents two possible causes of the asthma death rate increase. 1. More widespread and accurate recording. 2. Increase in urban air pollution. In the following sentence, the author then rejects both of these theories. Cities with long-standing medical records and little pollution experienced the same asthma death trend. With the first two theories debunked, the author presents a third possible cause: bronchial inhalers. The only support for the inhaler theory is the rejection of the other theories, as if there were only three possible options. The author's argument completely depends on rejecting the first two possibilities. You are correct when you say that answer choice B contradicts the third sentence. This is supposed to happen! It is not so simple that we can call any contradiction "weakening." In this case, answer choice B contradicts an opposing theory, thus strengthening the argument.