<span>D. Great Britain
Hope this helps!</span>
The primary difference between barter and currency systems is that a currency system uses an agreed-upon form of paper or coin money as an exchange system rather than directly trading goods and services through bartering.
The author who proposed the theory of "natural selection," which other people called "survival of the fittest" was named Charles Darwin. These two ideas are the founding basis of the theory of evolution.
In a social system, there are peers and strangers to distract one from pursuing their work. While chatting with others, you may forget your train of thought or a good idea. People are likely to take you away from your work more so than a physical system (in which you can always turn off the TV, but not get people to quiet down)
Answer:
<h2>
South Vietnam was reunited by force with North Vietnam and became a single communist nation.
</h2>
Explanation:
The US had been supporting South Vietnam against the communist North Vietnam. Ultimately, US President Richard Nixon proposed drawing down US involvement in the war and seeking "peace with honor," as he put it.
Once the US forces withdrew (after a long, unsuccessful struggle), it was too late for the South Vietnamese to stave off the victory of the North Vietnamese and Viet Cong forces. The US withdrew its forces from Vietnam in 1973. By 1975, Saigon, the capital of South Vietnam, fell to the North Vietnamese communist forces. South Vietnam unconditionally surrendered to North Vietnam on April 30, 1975. All of Vietnam became united under communist control.
