Answer:
Water distribution
Explanation:
The human body uses water in all their cells as matter fact the tissues in body and brains need water to regulate the flow of temperature. As energy is needed for breathing and sweating and digestion also hence the water is needed as important component in the body and thus its prope distribution is a must. 95 percent of human body is amd up of water in the from of fluids, without water civilization would not have existed.
I would say that the US and the Soviet Union at the end of WWII withdrew their troops as soon as a demilitarized zone was created. Also, I am sure they would require a peace treaty to be signed with Germany before withdrawing troops.
It's is called sustainability
Sea Food and water mostly.
From smallest to largest it would be individual, population, community, ecosystem, biome, and then biosphere.