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题库 / OG2016-CR-68
Which of the following most logically completes the argument?
By competing with rodents for seeds, black ants help control rodent populations that pose a public health risk. However, a very aggressive species of black ant, the Loma ant, which has recently invaded a certain region, has a venomous sting that is often fatal to humans. Therefore, the planned introduction into that region of ant flies, which prey on Loma ants, would benefit public health, since _________.
ant flies do not attack black ants other than Loma ants
Loma ants are less effective than many bird species in competing with rodents for seeds
certain other species of black ants are more effective than Loma ants in competing with rodents for seeds
the sting of Loma ants can also be fatal to rodents
some pesticides that could be used to control Loma ants are harmful to the environment
情景：黑蚂蚁对人类是有帮助的，但是有一种叫Loma 的蚂蚁确实有害。为了控制这种蚂蚁的数量，推理文段给出了“引入ant flies”的方法。推理文段的结论句为：The planned introduction into that region of ant flies, which prey on Loma ants, would benefit public health.
推理：本题的推理结构为：
目标：To benefit public health ( 让公共卫生获益)
方案：Introduce ant flies
选题方式：方案推理有三个评估方向，简而言之，即，答案选项一定和方案的内容相关。
选项分析：
A选项：Correct. Ant flies 不会攻击除了Loma ants 以外的黑蚂蚁。本选项排除了一个引入ant flies 可能带来的副作用，可以加强推理文段，属于CQ3：方案的否定性副作用。
B选项：Loma ants 在和啮齿类动物争夺种子方面不如很多鸟有效率。本选项没有提及方案，可以排除。
C选项：某些黑蚂蚁在夺种子方面比Loma ants 更有效率。本选项没有提及方案，可以排除。
D选项： Loma ants 的叮咬对啮齿类动物也可能是致命的。本选项没有提及方案，可以排除。
E选项：某些可以控制Loma ants 的杀虫剂会造成环境污染。本选项没有提及方案，可以排除。
方案推理，新方案都不是选项。
题目重点：引进L的天敌有利于人类健康。
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