请教prep-1-15, 航空公司提价

虽然这道题目可能很简单，但是我就是转不过弯来，哪位NN帮我理下这道题的解题思路。

我排除了A C E，强烈的觉得B不是weaken，是support。估计是钻进怪圈了，大家把我拎拎出来吧，BOW!

15.  

Some airlines allegedly reduce fares on certain routes to a level at which they lose money, in order to drive competitors off those routes.  However, this method of eliminating competition cannot be profitable in the long run.  Once an airline successfully implements this method, any attempt to recoup the earlier losses by charging high fares on that route for an extended period would only provide competitors with a better opportunity to undercut the airline's fares.

(A) In some countries it is not illegal for a company to drive away competitors by selling a product below cost.

(B) Airline executives generally believe that a company that once underpriced its fares to drive away competitors is very likely to do so again if new competitors emerge.

(C) As part of promotions designed to attract new customers, airlines sometimes reduce their ticket prices to below an economically sustainable level.

(D) On deciding to stop serving particular routes, most airlines shift resources to other routes rather than reduce the size of their operations.

(E) When airlines dramatically reduce their fares on a particular route, the total number of air passengers on that route increases greatly.

本题的结论是降价赶走竞争对手的举措是无效的，weaken这个结论就是要证明这个举措是有效的。

题干说无效的理由是“先降价赶走竞争者，再提价会导致竞争者重新回来”。B反驳了这一点，说一旦发生这种情况，公司可以重新降价，因此证明了降价举措有效，从而weaken了结论。

有点朦胧的醍醐灌顶的感觉了，谢谢ls的！

“说一旦发生这种情况，公司可以重新降价，因此证明了降价举措有效，从而weaken了结论。”我怎么觉得这个论证方法就这么的绕呢...

BTW,重新看了下我当时选的D，确实是无关选项。但在时间很紧的情况下做题，迷惑性还是很大的。

怎么能提高时间紧情况下，题目的一次正确率呢～ 头疼ing