【正确答案】 B

【答案解析】Argument Evaluation
Situation Poor farmers receive higher prices for fair-trade coffee. But paying extra for fair-trade coffee lowers prices for non-fair-trade coffee and thus lowers profits for non-fair-trade coffee farmers
Reasoning What would be most helpful to know to evaluate how well the economist's observations support the conclusion that buying fair-trade coffee hurts more farmers in developing nations than it helps? The economist suggests that buying fair-trade coffee benefits farmers who grow it because they receive higher prices, but that it hurts non-fair-trade coffee farmers by reducing their profits. So to knew whether the practice hurts more farmers in developing nations than it helps, it would be helpful to know whether developing nations have more farmers who produce non-fair-trade coffee than produce fair-trade coffee.
A Even if there were some potential way of alleviating the negative impact from buying fair-trade coffee on non-fair-trade coffee farmers, it still could be that the practice hurts more developing-nation farmers than it helps. Alleviating the negative impact does not entail that there is no negative impact.
B Correct. If fewer than half of these farmers produce fair-trade coffee, then the economist's observations do suggest that buying fair-trade coffee hurts more coffee farmers in developing nations than it helps. But if more than half do, those observations suggest the contrary.
C Although knowing this could be helpful in determining how intensely many farmers are economically affected by people buying fair-trade coffee, it is not helpful in determining whether more farmers are hurt than are helped.
D The argument's conclusion is only about the economic impact of buying fair-trade coffee, not about how consumers should or should not respond to that impact.
E Knowing how the fair-trade coffee farmers could potentially be helped without hurting the other coffee farmers is irrelevant to assessing whether the practice of buying fair-trade coffee hurts more developing -nation farmers than it helps.
The correct answer is B.