考查事实细节。根据关键词by 2050 定位到文中第三段We need economic growth unless we condemn (使注定) the world's poor to their present poverty and freeze everyone else's living standards. With modest growth, energy use and greenhouse emissions more than double by 2050. 国家要发展经济，即使是适度的经济增长也会使温室气体排放量达到现在的两倍以上，意思就是说温室气体排放量到2050 年翻倍的原因就是经济的增长。04.The author believes that, since the signing of the Kyoto Protocol, _______.
Apoliticians have started to do something to better the situation
Bfew nations have adopted real tough measures to limit energy use
Creductions in energy consumption have greatly cut back global warming
Dinternational cooperation has contributed to solving environmental problems