Hunter-gatherer societies had the benefit of a-good farming techniques b-their understanding of germs c-sophisticated tools d-knowledge of the environment

Your answer would be D- Knowledge of the environment.
I hope this helped... ;)

Hunter-gatherer societies had the benefit of knowledge of the environment.

They would want to move in any kind of a location to the point that they could move where ever they would want to move, and they wouldn't have to worry about this and that because they would just be so familiar about where everything would be at, which in this case, we can see in the option how it would read "knowledge" of the (environment) which would show that they would understand where they would be located.