Answer:
The answer is D. It made it less time consuming and saved workers energy.
I would say B. Rivers provided a source of both water and transportation.
This would have to be true, as the great amount of waterways connecting the region would allow for transportation and a supply of water.
Both joints have an ulna and a radius connected to them. Both joints are hinge joints, however humans have a complex hinge joint (allowing us to move it in more directions) while cows have only a hinge joint (can only move in one direction).
