Question from GMAC GMAT Review 11th Edition

[pranavc]

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 its 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 markets to foreigners to protect domestic producers.

I know the answer but I cannot for the life of me figure out how to arrive at it. Any input would be much appreciated. Thanks in advance.

Pranav

[netigen]

Look at the conclusion:

If every country acted according to its theory, no country would trade with any other.

This is only possible if there is a chain reaction, which is possible only if out of every two countries in the world one has some market closed to the other.

Do a logical negation of ans D

For any two countries, none has some market closed to the other.

If this were true the conclusion is weakened hence D is the correct answer.

[pranavc]

The logical negation angles really helps. Thanks a lot.

Pranav

[khanshainur]

answer is clearly A