Economist: Prosperity is a driving force behind increases in the release of carbon dioxide, the main cause of global warming. As incomes rise, more people spend money on energy-consuming devices such as cars, thereby producing more carbon dioxide. Also, in countries that experienced deep economic recessions, there were steep drops in carbon dioxide emissions. Which one of the following most accurately states the overall conclusion drawn in the economist's argument? ['When incomes rise, more people spend money on energy-consuming devices.', 'When people spend money on energy-consuming devices, more carbon dioxide is produced as a result.', 'Prosperity is an important cause of increases in the release of carbon dioxide.', 'Carbon dioxide is the main cause of global warming.']