Student: If a person has an immunity to infection by a microorganism, then that microorganism does not cause them to develop harmful symptoms. Since many people are exposed to staphylococcus without developing any harmful symptoms, it follows that they have an immunity to infection by this microorganism. The student's argument is most similar in its flawed pattern of reasoning to which one of the following? ['Isabel said that she would take the medication. Obviously, though, she did not do so, because medication either cures disease or alleviates its symptoms, and Isabel is still quite ill.', 'Everything morally right is just, but some actions that best serve the interests of everyone are not just. Thus, some morally right actions do not serve the interests of everyone.', 'Studies show that doctors tend to wash their hands less often than any other health care professionals. This shows that the procedure cannot be of much value in preventing disease.', 'When business owners are subjected to excessive taxation, they become less willing to expand their businesses. The recent decline in business expansions thus shows that their taxes are too high.']