Did you try reading them all and looking at notes?
Answer:
The Kyoto Protocol, signed in Japan in 1997, was an international, multilateral treaty aiming at curbing emissions of greenhouse gases and their levels in the atmosphere. It set goals and quotas for both the developed and the developing world. The greenhouse gases are responsbile for global warming. Carbon dioxide, methane, nitrus oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride are greenhouse effect gases.
Explanation:
An aristocracy, middle class, and slaves are examples of a "social" structure, although it should be noted that elements of culture, politics, and religion are often intertwined in such categorizations.
I think it might be either C or D but I'm not to good at this stuff (p.s I like alMystic Messenger too!)