with whiCh oF thE Following topiCs is thE pAssAgE mAinly ConCErnED
A．thE rolE oF thE rAilroAD in thE EConomy oF thE unitED stAtEs.
B．mAjor ninEtEEnth-CEntury writErs.
C．thE ConFliCt BEtwEEn ExpAnDing inDustry AnD prEsErving nAturE.
D．thE rAilroAD As A suBjECt For litErAturE.