Ninety percent of recent car buyers say safety was an important factor in their purchase. Yet of these car buyers, only half consulted objective sources of vehicle safety information before making their purchase; the others relied on advertisements and promotional materials. Thus, these other buyers were mistaken in saying that safety was important to them. The argument's conclusion follows logically if which one of the following is assumed? ['Someone who claims that safety was an important factor in a buying decision does not necessarily mean that safety was the most important factor.', 'Advertisements and promotional materials sometimes provide incomplete vehicle safety information.', 'Most consumers are aware that advertisements and promotional materials are not objective sources of vehicle safety information.', 'Anyone to whom safety is an important factor in purchasing a car will consult an objective source of vehicle safety information before buying.']