Furthermore all merchants arriving from India or other countries, and bringing with them gold or silver or gems and pearls, are prohibited from selling to any one but the Emperor. He has twelve experts chosen for this business, men of shrewdness and experience in such affairs; these appraise the articles, and the Emperor then pays a liberal price for them in those pieces of paper. The merchants accept his price readily, for in the first place they would not get so good a one from anybody else, and secondly they are paid without any delay. And with this paper-money they can buy what they like anywhere over the Empire, whilst it is also vastly lighter to carry about on their journeys. And it is a truth that the merchants will several times in the year bring wares to the amount of 400,000 bezants, and the Grand Sire pays for all in that paper. Which of the following best explains a cause of the economic activity described in the passage?

the large-scale migration of Indians into western China
the outbreak and spread of the bubonic plague
the unification of the Eurasian trading network under the control of China’s economic system
the increase in long-distance trade as a result of Mongol-protected Silk Roads

Of course it could have been avoided. a great many scholars argue it happened because of truman's use of fear to gain support. his predecessor fdr was the most popular and charismatic president ever. truman was a machine politician chosen as the least offensive choice around for vp. had henry wallace remained vp and then president, the cold war might not have happened. or had dewey been defeated in the primaries by robert taft, and then taft defeated truman in 48, the cold war also might not have happened. taft was somewhat isolationist, opposing nato and the korean war. wallace believed truman to be unnecessarily provocative in his dealings with the soviets.of course for strong anti communists, they claim the soviets would see any sign of weakness and try to take over the world. but this is a conspiracy theory not backed by evidence. most communist movements were local and not controlled by moscow. stalin had just lost over 20 million people and was exhausted and paranoid. his number one fear was a rearmed germany allied with the us, and truman made his nightmare real with the marshall plan. truman's blunders are at least half responsible for the cold war and neither wallace nor taft would have made them.on top of that, stalin was dying and in poor health. his successor khrushchev was a reformer who ended the forced labor camps, set many political prisoners free, criticized stalin, and declined to build a powerful soviet navy to confront the us. stalin actually proposed a neutral united germany. a paranoid american gov't turned him down, guaranteeing a continued cold war for decades more.