Commentator: The theory of trade retailation states that countries closed out of any of another country's markets should close some of their own markets to the other country in order to pressure the other country to reopen its markets.If every country acted according to this theory, no country would trade with any other. The commentator's argument relies on which of the following assumptions? A. No country actually acts according to the theory of trade retailation. B. No country should block any of its markets to foreign trade D. For any two countries, at least one has some market closed to the other. 选D。这题是说如果两国互相关闭市场，就没有国际贸易存在了。A和B我觉也都说的有道理，错在哪了？？ | 
