【正确答案】 D

【答案解析】[听力原文]
Every ten years the United States conducts a census of the population. A census is account of the number of people who live in a city or a country. The government uses this information to get a better picture of its residents.
The last census was in 1990. In 1990, the population of the United States was about 250 million people. In 1980, ten years before that, the population was 227 million. That means the population is up 23 million people. This country is growing by about two million people a year.
The population of the United States is changing. In the past, more people lived in the North and the Midwest. Now, these areas are staying the same in population or declining. Today, more people are living in the South and the West. These areas are growing.
Look at the numbers from the 1990 census. The population of New York City is up only 4%, the population of Boston is up just 2%. In Pennsylvania, the population of Pittsburgh is down 13%. In Michigan, the population of Detroit is down 2%.
At the same time, cities in the South and West are growing. In California, the population of San Jose is up 24% and Bakersfield is up 66%. In Texas, Austin is up 35% and San Antonio is up 19%. Nevada has the largest population increase of any state. Reno is up 33% and Las Vegas is up 57%. Florida continues to grow. For example, the population of Orlando is up 28%.
Why is the population map changing? The number one reason is jobs. Many large industries in the Northeast are closing or moving to the South or out of the country. Also, in the past, there were thousands of small family farms in the Midwest. Now the farms are very large and machines do most of the work. Most new jobs are in the South and West. There"s a need for builders, teachers, and store owners. The second reason that the South and West are growing is that the population is getting older. More people are retiring and they are choosing warm, sunny climates near the coast. Finally, many new immigrants are deciding to settle in the South and the West. For many, the climate is similar to that of their native countries and it is easier to find a job.