People who browse the web for medical information often cannot discriminate between scientifically valid information and quackery. Much of the quackery is particularly appealing to readers with no medical background because it is usually written more clearly than scientific papers. Thus, people who rely on the web when attempting to diagnose their medical conditions are likely to do themselves more harm than good. Which one of the following is an assumption the argument requires? ['People who browse the web for medical information typically do so in an attempt to diagnose their medical conditions.', 'Many people who browse the web assume that information is not scientifically valid unless it is clearly written.', 'People who attempt to diagnose their medical conditions are likely to do themselves more harm than good unless they rely exclusively on scientifically valid information.', 'People attempting to diagnose their medical conditions will do themselves more harm than good only if they rely on quackery instead of scientifically valid information.']