【正确答案】 C

【答案解析】[听力原文]
   The shopping malls are designed for only one thing: encouraging people to buy, buy, buy. How do they do this? Well, it is something of an art, an art that has been brought to perfection in about 60 years since malls first started appearing in America.
   Every aspect of mall design is carefully calculated to appeal to the customer's psychological needs. This starts with the overall environment. Tests have shown that people feel most relaxed and comfortable at a temperature of 24-26 degrees. So, this is the air temperature of most malls. If it is any hotter, people may become too lazy to walk. Any cooler, they may rush around and leave before they've spent enough money.
   The choice of colors is also very important. Dark colors like orange or purple can make people feel irritable or unhappy. With such feelings, they are not likely to do much shopping. Therefore, very dark colors are almost never used in malls. Instead, walls are usually painted in light colors, which make customers feel relaxed and give the mall a spacious feeling.
   The arrangement of space in the mall is also done with great care. Research shows that most people are unwilling to walk more than two hundred meters to shop. In one of the new giant malls this could be a problem. There are two ways to deal with the problem. The walkways in malls can be made curved or angled to hide their true length. Or they can be broken up by fountains, art displays or any of those other things that you thought were just there to entertain you.
   The arrangement of the stores in a mall is relatively easy. The big department stores are the major attractions that encourage people to come to the mall. These should be kept well apart. Stores selling the same items should also be kept far apart, so that anyone who is comparing prices has to go past as many other stores as possible. After all, up to 60% of all items bought in malls are purchased on impulse.
   How long ago did malls first appear in America?