单选题 从下面提供的答案中选出应填入下列英文语句中______内的正确答案。
   All of these applications will enhance the (1) oflife and spur economic growth. Over half of the U.S. work force is now in jobs that are information (2) . The telecornmunication and information sector of the U.S. economy now (3) for 12 percent of the Gross Domestic Product, growing much faster than any other sector ofthe economy. Last year the (4) in this sector exceeded 700 billion dollars. The U.S. exported over 48 billion dollars of telecommunication equipment (5) .