Here I send you an attachment of the complete answer, I hope you're able to open it.
It means in a context of a two-party system. Like if opposing parties find a common ground in a dispute.
Answer:
in some books yes and some no
Explanation:
The main idea of this paragraph is that the rocks cannot be explained by science, that there is a mystery to them. This sentence contributes to that idea because it gives a specific example of one of the odd things about the rocks. Because they are on a flat surface they should not roll or move on their own, but the fact that they have a trail behind them shows that they have somehow moved. This supporting statement is then supported by more details about the trails.
