Elk（麋鹿） now live almost solely（单独地） in the Rocky Mountains, which would make it seem that elk are mountain dwellers（居住者）, while they once ranged over virtually all of the continental United States except for a small strip in the extreme Southwest.

1. Elk now live almost solely in the Rocky Mountains, which would make it seem that elk are mountain dwellers, while
                                 which不能指代句子肯定不对
2. The fact that elk now live almost solely in the Rocky Mountains would make it seem that they are mountain dwellers, but
3. It would seem that elk would be mountain dwellers because of their living now solely almost in the Rocky Mountains, but still
                                用词错误，still 多余
4. Now living almost solely in the Rocky Mountains, it would seem that elk were mountain dwellers, although
                                VING置于句首，后面应紧跟其修饰对象
                           

5. It seems that elk would be mountain dwellers from the fact that they now live solely almost in the Rocky Mountains, since
                           连词错误，不合句意，from the fact that 感觉不妥

答案是A，我觉得选B，请大家帮忙看看

they are mountain dwellers

但是B 中的they 这的代词指代肯是不如A清楚的

而且B 的主语变成了the fact,  but 后面的并列也不是很好了

如果是B的话, 且不说it 指代谁的问题, 至少应该是it seems that 吧? 主谓一致应该作为一级错误排除. 我还是选E