【正确答案】 C

【答案解析】[听力原文]14-17
Television carries more national advertising than any other in the United States. The same is true in some smaller countries such as Spain and Portugal, where it is the only medium reaching a general national audience. In many countries--Sweden and Denmark, for example--the state-owned television accepts no advertising. In many other countries the amount of commercial time is extremely limited, as in France, Germany, and Italy. Soviet state-owned television began accepting a limited amount of advertising in 1988.
The chief reason for the popularity of television among United States advertisers is that it reaches a vast number of people at the same time. While it can cost well over 100,000 dollars, a 30-second commercial on network television can be seen and heard by as many as 25 million viewers. For manufacturers who must make prospects aware of their products and convince them of its benefits immediately, there is nothing as efficient as television advertising.
Because it employs motion as well as words, pictures, sound, and music, television is a valuable medium for products on display. No other medium is as effective in showing how quickly an automobile can accelerate or how well a brand of wristwatch will stand up under abuse and continue to run. Similarly, it is an ideal medium for conveying a mood or an emotional benefit for products such as long-distance telephone calls.

此题是测试原因的事实细节题，根据文中“Television carries more national advertising than any other in the United States. The same is true in some smaller countries such as Spain and Portugal，where it is the only medium reaching a general national audience.”可知答案是C。