Mark: The decongestant drug Zokaz was discontinued by its manufacturer because long-term studies revealed that it increased the risk of heart attack. Qualzan, another decongestant, works by essentially the same physiological mechanism as Zokaz. So Qualzan probably also increases the risk of heart attack. Kathy: The decongestive effects of the two drugs do stem from the same physiological mechanism. But since they are different chemically, the two drugs probably have different side effects. Which one of the following is a technique of reasoning used in Kathy's response to Mark? ['attempting to discredit an argument by comparing it to another obviously flawed argument that is logically parallel', 'arguing against a conclusion by raising questions about the validity of scientific studies cited in support of that conclusion', 'challenging an argument from analogy by focusing on a dissimilarity between the things being compared 9', 'attempting to undermine an argument by showing that it is incompatible with a fundamental principle of medicine']