How would a archeologist found out how a civilization collapsed?

I think that they should find like old artworks like statues or documents and do some research on when that stuff was made and determine if that civilizations that the statue or whatever was originated and do research on that civilization and how it fell.

Hope this helped :)
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The answer is cultural

The answer to this question is  c. pharmaceutical accumulation  reclaimed water refers to the water that being used again after it already  used for agricultural purposes.this type of water often contains pharmaceutical accumulation because of the chemical fertilizer that is used for the plants is absorbed into the water.