whiCh oF thE Following is truE ABoutAmEriCAn trAnsportAtion systEm A、only thosE who ArE wEll oFF CAn AFForD to trAvEl By plAnE.B、trAins run EvEn slowEr thAn CArs.C、pEoplE prEFEr to tAkE trAins EvEn thEy ArE slowEr thAn plAnEs.D、CArs ArE prEFErrED ovEr plAnEs.