It was caused by the sharp rise in the price of opium was seized upon by some of the Cohong trading houses and smugglers.
Extremists groups such as ISIS are disrupting the peace and diplomacy by blowing up buildings and killing citizens. This means the correct answer is A.
Trade barriers restrict or reduce international trade which reduces international cooperation among states and the overall interdependence. For example, if you rely on another country to buy cocoa and they rely on you to get sugar, if you enact trade barriers, you won't get cocoa and they won't get sugar which will be a huge problem for both industries in both countries because you depend on each other.
