The main way in which anthropologists are able to make generalizations about human behavior is by looking at how they used to live their life--their tools, migration patters, war tactics, etc--which are very similar throughout populations.
There were several major factors that led to stalemate in the trenches, but the best options from the list are "Defensive weapons were better than offensive ones.
<span>and Trenches were designed for defense."</span>
To experiment the force of gravity between masses
To stop Germany from taking over the world and to keep them from destroying our shipping
