With the development of industry and extension of railroad netwo

With the development of industry and extension of railroad network in the early 20th century in the U.S.A., there appeared ______.
A、a rapid growth of cities
B、an influx of foreign goods
C、an increase of urban ghettos
D、a great increase in the number of farms
【正确答案】：A
【题目解析】：20世纪初，随着美国工业的发展和铁路网的延伸，美国铁路运输的发展迅速在美国，出现了快速发展的城市。