96 Commentator: The theory of trade retaliation 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 retaliation.
(B) No country should block any of its markets to foreign trade.
(C) Trade disputes should be settled by international tribunal.
(D) For the two countries, at least one has some market closed to the other.
(E) Countries close their markets to foreigners to protect domestic producers.
OG explanation:
Argument construction
Situation: The theory of trade retaliation is explained as the action and reaction of closing markets between trading nations; no country would ever trade with another, the observation is offered, if every country acted according to the theory.
Reasoning: What assumption underlies this argument? What makes the commentator conclude that no country would be trading if the theory were operative? The commentator must perceive of some condition as a given here. The argument assumes an initial action, a country's closing of a market to a trading partner, that is followed by a reaction, the retaliatory closing of a market by that partner. In this unending pattern of action-reaction, at least one of the two countries must have a market closed to the other.
A Any one country may act according to the theory, but not every country.
B The argument assumes that countries do block markets to foreign trade.
C An international tribunal is not mentioned in the argument.
D Correct. This statement properly identifies the assumption required to create the never-ending action-reaction pattern.
E The argument does not discuss the protection of domestic trade.
The correct answer is D
我的问题是，我看不懂题干的意思，我不是经济商科类背景的，哪位好心人能帮我解释一下这句话隐含的经济规律？
The theory of trade retaliation 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. | 
