[单项选择]Fast food, a mainstay of American eating for decades, may have reached a plateau in the United States as the maturing baby-boom generation looks for a more varied menu. Fast foxed still represents a $102 billion a year industry, but growth has turned sluggish recently amid tough competition from retail food stores and a more affluent population willing to try new things and spend more, analysts say. Signs of trouble in fast food include price-cutting by industry leaders, including efforts by McDonald’s to attract customers with a 55 cent hamburger, and major players pulling out or selling. O’Pepsico, for example, is selling its fast-food restaurant division that includes Taco Bell, Pizza Hut and KFC. "It’s becoming harder and harder for these firms to grow," said Jim Brown, a professor of marketing at Virginia Tech University. "I think in the United States fast food has reached a saturation (饱和) point because of the number of competitors and the number of outlets." Fast-f A. O’Pepsico goes bankrupt. B. The number of supermarkets doubles. C. Jim Brown takes a negative attitude towards the development of fast food. D. McDonald’s survives from the competition with retail food stores.