单选题 One major obstacle to economic development is population growth. The populations of most developing countries grow at a rate much faster than that of in dustrialized countries. One reason for this growth is the high crude birth-rate—the number of live births per 1,000 people.
A. to
B. The populations
C. that
D. live births

【正确答案】 C

【答案解析】[解析] B和C选项形成比较。B选项为复数形式，因此C选项也应该使用复数形式，因此，应改为those。因此，C选项为正确选项。