阅读下列短文：从每题所给的 A、B、C、D 四个选项中，选出最佳选项，将正确的选项涂在答题卡上。

Is there link between humans and climate change or not? This question was first studied in the early 1900s. Since then,many scientists have thought that our actions do make a difference. In 1997,the Kyoto Protocol explained our role in the Earth's changing atmosphere and set international limits for gasemissions(排放) from 2008to 2012. Some countries have decided to continue these reductions until 2020. More recently, the Paris Agreement, stuck by nearly 200 countries, also aims tolimit global warming. But just now how much warmer it will get depends on how deeply countries cut carbon emissions.