t is a typical Christmas electronics shopping season, and makers of ultra-high-definition TVs (UHDTVs) are marketing the latest available models through their own websites as well as via retailers such as Best Buy and Walmart. Each manufacturer offers its own unique versions of UHDTVs in differing arrays of shapes and sizes. As usual, each is hoping to maintain a stream of economic profits earned since it first introduced these most recent models late last year or perhaps just a few months before Christmas. Nevertheless, as sales figures arrive at the headquarters of companies such as LG, Samsung, Panasonic, and Sony, it is clear that most of the companies will end up earning only a normal rate of return this year. Part 2 How can makers of UHDTVs earn economic profits during the first few months after the introduction of new models? Part 3 A. New models create product differentiation that increases demand and raises prices above average total cost. Thus, firms will earn positive economic profits in the long run. B. New models create product homogeneity that increases demand and raises prices above average total cost. Thus, firms will earn positive economic profits in the long run. C. New models