Q41:
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

答案选E，请问A错哪里了？那个which的用法是不是不对？如果去掉which，或者用which was对吗？

A中which引导的定语从句缺少谓语啊，加上was之后语法上不错吧，但是与E比较还是觉得E好。。。仅供参考

谢谢！