Read the following excerpt about the invention of refrigerators and answer the question that follows. It wasn't until 1930, when Frigidaire began cooling with chlorofluorocarbons (CFCs), that people began upgrading to refrigerators. Small, with big fans on top, the appliance changed the way America ate. Manufacturers provided books with menus for a lifestyle that included ice tongs, bridge parties, and recipes showing off all that a refrigerator could do for a single meal. (In 1929, Kelvinator suggested a raspberry cup, molded lamb, celery curls, and Kelvinator fruitcake with whipped cream.) Pre-fridge, "frozen desserts and frozen salads were nonexistent or just for wealthy people," says Sylvia Lovegren, author of Fashionable Food: Seven Decades of Food Fads. "All of a sudden, the middle class could have things that seemed high class a few years before." And what could be more high class than frozen cheese salad or an icy frappe made of condensed tomato soup? Which of the following details should be included in a summary of an article about the history of refrigerators?