The greatest road system built in the Americas prior to the arrival of Christopher Columbus was the Incan highway, which, over 2,500 miles long and extending from northern Ecuador through Peru to Southern Chile.
- Columbus was the Incan highway, which, over 2,500 miles long and extending
- Columbus was the Incan highway, over 2,500 miles in length, and extended
- Columbus, the Incan highway, which was over 2,500 miles in length and extended
- Columbus, the Incan highway, being over 2,500 miles in length, was extended
- Columbus, the Incan highway was over 2,500 miles long, extending
本人选的是B，答案是E，偶觉得E中的两个句子之间（即The greatest road system built in the Americas prior to the arrival of Christopher Columbus,和the Incan highway was over 2,500 miles long），没有连接词，这个对吗？谢谢！ | 
