一道GWD的sc

mike125615212

Competitionin the mid-nineteenth century by large western farms gradually caused farmersin Pennsylvania to turn to livestock raising, but before that it waspredominantly grain-producing.

1. Competition in the     mid-nineteenth century by large western farms gradually caused farmers in     Pennsylvania to turn to livestock raising, but before that it was     predominantly grain-producing.[C1]
   
2. Once predominantly a     grain-producing state, competition in the mid-nineteenth century from     large western farms gradually was causing Pennsylvania’s farmers to turn     to livestock raising.[C2]
   
3. Pennsylvania’s farmers were     gradually caused to turn to livestock raising by competition from large     western farms in the mid-nineteenth century, but before that it was     predominantly a grain-producing state.[C3]
   
4. It was once predominantly     grain-producing, but competition in the mid-nineteenth century by large     western farms was gradually causing Pennsylvania’s farmers to turn to     livestock raising.[C4]
   
5. Pennsylvania was once a     predominantly grain-producing state, but competition in the mid-nineteenth     century from large western farms gradually caused the state’s farmers to     turn to livestock raising.[C5]
   

这个题给的答案是E但是我觉得，E和A的句子中心完全不一样了，怎么还能成为正确答案呢？百思不得其解啊！！求大神解答！！！

mike125615212

为什么呀？难道改变句子意思不算错吗？

mike125615212