求助一道PREP逻辑题！！！

wsyzzydy

Most of the world's supply of uranium currently comes from mines. It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market.Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

(A) Whether the uranium in deposits on land is rapidly being depleted

(B) Whether most uranium is used near where it is mined

(C) Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater

(D) Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land

(E) Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater

答案为什么是A呢？？我觉得C说有技术进步可以减少COST对原文起到加强作用啊~求解释！！

eshopaholic

C 已经在结论的假设里出现了，再提无意义。

A 有价值，如果矿都开完了，那铀的市价必然会炒得很高，那海洋开采技术就有商业价值了

haosir1234

C在讨论有没有这种先进技术，无关选型。
A讨论的是陆地资源有没有用光，这是影响开矿的前提。

脑子比头大

题目都已经说了"until the cost of extracting uranium  from seawater  can somehow be reduced"，就说明已经排除了降低成本这个因素，降低成本已经不再考虑范围之内了，所以C不对！就像是你老板对你说，给我提出一个提高员工士气的方案，除了多发工资之外，什么方案都行。结果你说，我的方案是，通过增发工资来提高员工士气。老板不被气疯了才怪~