OG上的逻辑题

nancyyue1219

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 any two countries, at least one has some
market closed to the other.
(E) Countries close their marketsto foreigners to
protect domestic producers.
这道题一直不太能理解D是如何削弱选项的，有谁能教教吗？

chensong211

试着解答一下：
Conclusion: If every country acted according to this theory, no
country would trade with any other.
Argument: 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 market
问题问的是argument里面的assumption, 这里的Argument里面有个gap，就
是why close markets will pressure other country to reopen its
market?

就像朝鲜说我要关了面向美国的市场，美国说那我也要关了朝鲜的市场，
这样就可以pressure朝鲜reopen market了么？
当然例子有点那啥。。不过意思就是如果俩国根本没啥close关系的话，那
就不会pressure to reopen market了

Sherryxqr

Necessary assumption. Use negation.

If you negate D), you have "For any two countries, neither has any market closed to the other". If this is the case and according to the trigger presented in the passage, not a single country would close out its market to any other country. The conclusion just falls apart. D) is the correct answer.

gonghao

我没有明白为什么negate D会反驳conclusion？怎么也转不过这个弯，跪求解答！