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题库 / GMATLA-CR-36
Because mining and refining nickel is costly, researchers have developed an alternative method for extracting nickel using Streptanthus polygaloides, a plant that absorbs and stores nickel from the soil as it grows. The researchers incinerated a crop of Streptanthus they grew in nickel-rich soil. By chemically extracting nickel from the ash, they produced 100 pounds of nickel per acre of land at a total cost per pound slightly above that of current mining.
Which of the following, if true, most strongly supports the conclusion that the use of Streptanthus to extract nickel will be commercially adopted?
The season in which the researchers grew Streptanthus was an unusually favorable one, with the right amount of precipitation to maximize the growth rate of Streptanthus.
Because lowering the concentration of nickel in the soil can make land much better for agriculture in general, a plot on which Streptanthus has been grown and harvested can be sold for substantially more than it cost.
More air pollution is generated for each pound of nickel produced by extracting it from Streptanthus than is generated using conventional mining and refining.
The land on which the researchers planted Streptanthus was unusually free of the various weeds that can compete with Streptanthus for water, nutrients, and sunlight.
It is extremely rare for soil to contain higher concentrations of nickel than the concentrations present in the researchers' experimental plot.
研究人员通过种随后燃烧植物的方式提取nickel ，可以比目前传统的mining+refining方式稍微高一点的成本得到nickel。问strengthen
choice a, 研究人员种植的季节特别适合植物生长，合适的降雨最大化植物的生长率。slightly weaken，说明在实际推广这个方法的时候有可能不会一直都是optimal condition，导致产量有可能到不了100 pounds ／arce. 同理choice d,也是slightly weaken
choice b, 因为移除了nickel的土壤更适合耕作，因此种过、燃烧过植物的土壤可以比成本价格卖得更贵。correct，说明plan带来了一个附加的好处
choice c, 通过植物提取nickel的方法比传统方法产生更多的空气污染。weaken，说明了一个副作用
choice e, 其他土壤很少能够含有比试验田里浓度更高的nickel。irrelevant
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