51. The author of an article about lifestyle trends concludes that, in general, people are not as concerned as they were a decade ago with regulating their intake of red meat and fatty cheeses. As evidence, the author cites the fact that a wide 0selection of high-fat cheeses is now available at a long-established grocery store, Heart s Delight, which specializes in organic fruits and vegetables and whole grains. The author further points out that the owners of the vegetarian restaurant next door, Good Earth Cafe, now make only a modest living while the owners of the new House of Beef across the street are millionaires. This argument is unconvincing. 来源：考试大 To begin with, the argument relies on the assumption that the dietary habits and attitudes of customers at these three businesses will reflect those of people generally. But the three businesses, all located in the same area of a single community, just might serve a clientele whose diets differ greatly from the diets of people in other areas of the community, or in other communities. The generalization that the author draws from this biased sample cannot be considered reliable. 来源：考试大 In addition, trends at these three businesses do not necessarily reflect the dietary habits and attitudes of their customers in the way the author claims. For example, we are not informed about how well the high-fat cheeses at Heart s Delight are selling relative to low-fat and nonfat alternatives. Similarly, it is possible that at House of Beef menu items other than red meat—such as chicken, fish, or salad bar—are just as popular as red meat among the restaurant s patrons. 来源：考试大 Finally, the author assumes that the financial conditions of the owners of the two restaurants were caused by a general lack of concern with regulating red meat and fatty-cheese intake. However, it is equally possible that the lackluster financial success of Good Earth was caused by mismanagement or increasing overhead costs. Furthermore, it is possible that House of Beef is generating little business, but its owners were already millionaires before they opened this restaurant or are making their money in other concurrent business endeavors. 来源：考试大 In conclusion, the author s evidence is too weak to support any conclusion about general dietary trends. Before we can accept the conclusion, the author must provide evidence from a representative sample of food-service businesses, and must clearly show that sates of red meat and fatty cheeses are increasing relative to sales of low-fat alternatives. The author must also provide evidence that the financial conditions of the owners of the two restaurants were actually caused by a general waning concern with regulating fat intake.来源：考试大