<span>B.the effect living and nonliving things have on each othe</span>
A the sixteenth amendment
The correct answer is A.
A market economy is characterized by no goverment intervention <em>(this rules out options B and C). </em><u>Therefore, property cannot be public and needs to be private</u>.
<em> </em><u>Economic decisions are reached by the free interactions (free competition) of the economic agents</u> (households, firms and public sector) in the domestic and international markets. Prices and exchanged outcomes are determined by the equilibrium between the desires of producers and consumers, both domestic and foreign ones, as a <u>market economy partcipates in globalization and market integration processes.</u> (which rules out option D).
The answer is A as river valley civilizations relied on rivers as a source of life. River valleys like Egypt, Mesopotamia and Xi, the rivers brought silt and made the soil very fertile, it also brought fresh water and fish to eat. People can also move fast using rivers.
I would argue that the primary difference was the introduction of nuclear weapons after WWII--meaning that the spread of communism could actually take over the world as opposed to just causing unrest in the US.
