求教！！~~~~

Prospecting for gold during the California gold rush was a relatively easy task, because of erosion, prehistoric glacier movement, and ancient, gold-bearing riverbeds thrust to the surface by volcanic activity put gold literally within reach for anybody with a pan or shovel.

1. because of erosion, prehistoric glacier movement, and ancient, gold-bearing riverbeds thrust to the surface by volcanic activity put gold literally within reach for
           
2. because of erosion, prehistoric glacier movement, and volcanic activity that thrust ancient, gold-bearing riverbeds to the surface, and putting gold literally within reach of

3. owing to erosion, prehistoric glacier movement, and volcanic activity that had thrust ancient, gold-bearing riverbeds to the surface, and putting gold literally within reach of
           
4. since erosion, prehistoric glacier movement, and volcanic activity that thrust ancient, gold-bearing riverbeds to the surface, putting gold literally within reach for

5. since erosion, prehistoric glacier movement, and ancient, gold-bearing riverbeds thrust to the surface by volcanic activity put gold literally within reach of

 这题我选了D，好像网上讨论答案是E真是百思不得其解！

NN能帮我分析一下这题的结构吗？

E correct.

E) Prospecting for gold during the California gold rush was a relatively easy task, since
            erosion, prehistoric glacier movement, and ancient, gold-bearing riverbeds
            (thrust to the surface by volcanic activity )
            put gold literally within reach of anybody with a pan or shovel.

The blue color words act as  the main structure of the sentence, while thrust is 被动 to modify riverbeds.

"that" is not allowed here infront of  "thrust".  However, if you really need it, you can add "that had been", but still not as concise as "thrust" itself.

D is wrong b/c it should be a complete sentence after "since". In this case, if you change "putting" into "put", then D will be correct.

谢谢，不过好像还不是很理解，先顶！~~~明天继续看！~