2010gmat wrote:Sven: Trade unions are traditionally regarded by governments and economists as restraints of trade, working against the complete freedom of the economy, but I believe that unions are indispensable since they are often the worker’s only protection against exploitation.
Ravi: I don’t agree. The exploitation of the workers and their work is a normal part of ordinary trade just like the exploitation of natural or other material resources.
Sven and Ravi will not be able to resolve their disagreement logically unless they
(A) define a key term
(B) rely on the opinions of established authorities
(C) question an unproved premise
(D) present supporting data
(E) distinguish fact from opinion

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iamcste wrote:

2010gmat wrote:Sven: Trade unions are traditionally regarded by governments and economists as restraints of trade, working against the complete freedom of the economy, but I believe that unions are indispensable since they are often the worker’s only protection against exploitation.
Ravi: I don’t agree. The exploitation of the workers and their work is a normal part of ordinary trade just like the exploitation of natural or other material resources.
Sven and Ravi will not be able to resolve their disagreement logically unless they
(A) define a key term
(B) rely on the opinions of established authorities
(C) question an unproved premise
(D) present supporting data
(E) distinguish fact from opinion

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IMO A

S talks about Trade unions, exploitation protection of workers specifically

E talks about general Trade, exploitation of workers and work

So, Key term of Argument equivocates.

2010gmat wrote:Great! you both knocked it...

How to approach these kind of problems? I felt that answer is E because both S and T are giving their opinions rather than basing their argument on fact....

And can anyone provide link to more such problems for practice?

B) rely on the opinions of established authorities

D) present supporting data