参考答案

正确答案：democracy and social justice
democracy and social justice 解析：参见第1个小标题 A Population Growth下面的第3段：In the developing world, meanwhile, the most important factors necessary to lower population growth rates are democracy and social justice．由此可知，在发展中国家中降低人口生K率的最重要的因素是民主政治和社会正义。