Answer:
Mainly Trench Warfare was popularized by the use of new mechanized weapons such as Artillery, and also because of the mass victories in the east on germany's side, Russia used these as a form of slowing them down and to protect their troops, but often these trenches hurt these men by disease, starvation, etc.
B is correct . (The adoption of the constitution with only 9 of the 13 states agreeing to it.)
Chinese River Valley civilization<span>although it was from 8000 to 2000 BCE
They used the river for irrigation and they raised pigs and chickens. Used stone tools</span>