求助狒狒逻辑一道题，怎么都绕不过来。。。

kakaka0523

23. On a certain day, nine scheduled flights on Swift Airlines werecanceled. Ordinarily, a cancellation is due to mechanical problems with theairplane scheduled for a certain flight. However, since it is unlikely thatSwift would have the mechanical problems with more than one or two scheduledflights on a single day, some of the nine cancellations were probably due tosomething else.
The argument depends on which one of thefollowing assumptions?
(A) More than one or twoairplanes were scheduled for the nine canceled flights.
(B) Swift Airlines has fewer mechanicalproblems than do other airlines of the same size.
(C) Each of the canceled flights would havebeen longer than the average flight on Swift Airlines.
(D) Swift Airlines had never beforecanceled more than one or two scheduled flights on a single day.
(E)All of the airplanes scheduled for the canceled flights are based at the sameairport.


答案是A，我做的时候觉得一个都不对就瞎猜了，但怎么都想不明白为什么是A，求指教

sdcar2010

Necessary assumption, use negation.

If you negate A, you get: NOT more than one or two airplanes were scheduled for the nine canceled flights.

If this is the case, than all the nine canceled flights were due to the problem of only 1 or 2 airplances. Then it is NOT an unusual situation for the airline and the nine cancellations were NOT due to anything else. The whole argument falls apart.  So condition C is required for the argument to hold.