三、阅读理解(30分，每题2分)阅读下面的三篇短文，根据文章内容从A、B、C、D四个选项中选出最佳选项。
Passage 1
African cities are forecast to urbanize(城市化)at a rate of 3.65% annually, adding nearly 350 million new city--dwellers by 2030, according to The Brookings Institution. A billion more people are expected to be living in African cities by 2063.
Population growth is the engine of urbanization f
