GWD 6-41

GWD GWD 6-41:

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.

A.       Columbus was the Incan highway, which, over 2,500 miles long and extending

B.       Columbus was the Incan highway, over 2,500 miles in length, and extended

C.       Columbus, the Incan highway, which was over 2,500 miles in length and extended

D.       Columbus, the Incan highway, being over 2,500 miles in length, was extended

E.       Columbus, the Incan highway was over 2,500 miles long, extending

我想请问下这里的Ｃ和Ｅ　选向　这里考的是不是修饰问题

Ｃ那里extended是修饰the Incan highway　　而Ｅextended是修饰  Columbus

对吗　我的理解？