Answer:
d. The rocks have stumped scientists because some roll, some take unexplainable routes, and some have traveled past ones that have stayed still, but scientists have theories that the rocks are pushed by wind or that they slide on ice or mud is the correct answer.
Explanation:
As seen in the question, the passage has two paragraphs: the first one refers to Drifting Rocks and it is basically about the context of this situation, like the place (Death Valley) and the trails.
In the second paragraph, we can see that the speaker describes the movement of the rocks and their routes; the paragraph also mentions some theories that scientists have. Due to this, <u>letter D is the correct answer.</u>
