Generally speaking, it would be that "D. European states had their borders clearly defined" that was an important outcome of the Congress of Vienna, since this increased stability in Europe after the Napoleonic Wars.
The best answer is laissez-faire.
The process of supply and demand is essential to the economic system of laissez-faire which is founded upon an absence of regulations or interference of anything outside of the natural economic interaction. Communism is incorrect because the economic markets are controlled by the government, and socialism is also incorrect because its economic markets are determined by participation, not value.
The correct answer to this open question is the following.
Although there are no options attached we can say the following.
The civil war tested the foundation of a country that uses democracy in that the civil war confronts people from the same country on the battlefield for political and economic reasons.
It is hard to believe that people from the same nationality -brothers we could say in a metaphorical way- confront each other to the extreme of seceding from the Union and fight using weapons. A civil war is an internal battle that hurts democracy and the legitimacy of the government that the founding fathers so carefully planned for the United States since colonial American times.
A civil war separates, divides. As President Abraham Lincoln said in his famous speech "A House divided," if a country is divided from within, this not only hurts democracy and freedom but also impacts all aspects and foundations of a nation.
The Lend-Lease Act provided weapons and such to the Allies during World War ll. The United States gave money to Allied countries to buy weapons from the United States.
