Read this excerpt from The Call of the Wild by Jack London.

Here was neither peace, nor rest, nor a moment's safety. All was confusion and action, and every moment life and limb were in peril. There was imperative need to be constantly alert; for these dogs and men were not town dogs and men.

What does the excerpt reveal about the setting of the story?

The lack of civilization is a persistent danger.
The demanding schedule requires heavy labor.
The hazardous equipment poses difficulty.
The overpopulation causes disputes.