[求助]prep一题

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 undermine 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 seawter 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

answer a

原文：u现在一般取自矿中，但是也可以在海水中提取。而在海水中提取u将会非常的贵

结论：直到在海水中提取u的花费降下来，这种方法才会被利用。

A评价：是否矿中的u将很快就会被采光了？

如果是，则不会等到在海水中提取u的花费降下来就采用这种方法

如果不是，那么人们将会如原结论所说：直到在海水中提取u的花费降下来，这种方法才会被利用