113 The difficulty with the proposed high-speed train line is that a used plane can be bought for one-third the price of the train line, and the plane, which is just as fast, can fly anywhere. The train would be a fixed linear system, and we live in a world that is spreading out in all directions and in which consumers choose the free-wheel systems (cars, buses, aircraft), which do not have fixed routes. Thus a sufficient market for the train will not exist. Which of the following most severely weakens the argument presented above? A. Cars, buses and planes require the efforts of drivers and pilots to guide them, whereas the train will be guided mechanically. B. Cars and buses are not nearly as fast as the high speed train will be. C. Planes are not a free wheel system because they can fly only between airports, which are less convenient for consumers than the high-speed train’s stations would be. D. The high speed train line cannot use currently underutilized train stations in large cities. E. For long trips, most people prefer to fly rather than to take ground-level transportation.
为什么选C，想不通。C不是等于反对前提了吗？ B为什么不对？
说实话这道题我就没有看出来是要把火车和飞机比，还是火车和Cars and buses比,还是火车和所有其他交通方式比。惭愧。。。
请各位指点，万分感谢！！ | 
