[单项选择]To swim across the English Channel takes at least nine hours. It’ s a hard work and it makes you short of breath. To fly over the Channel takes only twenty minutes ( as long as you’ re not held up at the airport), but it’ s an expensive way to travel. You can travel by hovercraft if you don’ t mind the noise, and that takes forty minutes. Otherwise you can go by boat, if you forget your sea-sickness ills. All these means of transport have their problems and the weary(不耐烦的) traveler often dreams of being able to drive to France in his own car. "Not possible", you say. Well, wait a minute. People are once again considering the idea of a Channel tunnel or bridge.
This time, the Greater London Council is looking into the possibility of building a Channel link straight to London. (79) A bridge would cost far more than a tunnel, but you would be able to go by rail or by car on a bridge, whereas a tunnel would provide a rail link only.
Why is this idea being discussed again I
A. Swimming across the Channel takes less than four hours.
B. The idea of a Channel tunnel or bridge is a very new one.
C. It is considered to be more difficult to swim across the channel than any other means.
D. A tunnel or bridge would only reach as far as the coast.