大家帮我看看，我觉得答案不对，一道支持题

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 form 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?

1. 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.
2. 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.
3. More air pollution is generated for each pound of nickel produced by extracting it from Streptanthus than is generated using conventional mining and refining.
4. 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.
5. It is extremely rare for soil to contain higher concentrations of nickel than the concentrations present in the researchers’ experimental plot.

答案给的是d，可是我觉得b才是更好的支持，请教了！

我开始也选的b, 仔细看好象b有点儿不沾边儿

题目问,哪些选项支持“种S来吸收镍”这种方法被采纳

b.因为降低土壤中的镍含量可以使土地更易于耕作,所以一块种S种得好的地块可以买更高的价格(相对于土地成本)

d.研究者种S的土地没有可与S抢水,养料和阳光的种子存在

这样看好像d更好，因为b中土地价格高低和题目有点儿远

再深想想，B选项可以认为是削弱，因为适合种 S的土地对种植者来说成本高了，说不定可以超出they produced 100 pounds of nickel per acre of land at a total cost per pound slightly above that of current mining所省下的钱。。。

支持B

原文结论是:用种S植物的方式提取N商业上(COMMERCIALLY)可行.简单说就是合算.B正是此意.

D最多无关或削弱.它和A意思接近,都是说作实验的那块的没代表性.A说那块地unusually favorable .D说那块地free of the various weeds.所以最多是削弱.

oops!没看清b说的是has been grown ...can be sold ... more

答案到底是啥啊...我比较墙头草,答案说啥我就能胡诌出啥。。。