问一道PREP里遇到的逻辑

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 attemp 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.

which of the following, if true, most seriously weakens the argument?

A. 省略

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. ~D.省略

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

The correct answer in the PREP is B.

My question is, if B is correct, when new competitors emerge, the company will once again cut prices of its fares, then how could this plan be profitable in the long run?? But E seems fallacious too, according to E the company actually didn't suffer losses to a degree as it has alleged...