How did the war change the structures and roles of some nations?

the balkan countries experienced a period of peace.

the german economy was able to recover from its war debt.

russia's government thrived under the czar's leadership.

the united states took on a new position as a world leader.

the German economy was able to recover from its War

The United States took on a new position as a world leader.

Explanation:

After the first world war the USA managed to establish its influence, becoming a great world power.

After the first world war, Europe entered a great moment of economic recession and a huge social crisis, in addition to having to deal with problems of independence of its colonies, among other things that left European countries at the mercy of the help of the Americans, who they had been affected by the war to a lesser extent.

The second world war only served to increase American influence among the countries. Not quite, the cold war sealed the US's influence and power in the rest of the world.

the correct answer is “opportunity cost”. opportunity cost is what a company misses out because it decided in one option over another one. in this case, the company decided to invest in building a factory so it gave up another possible benefit or profit in order to achieve success with the factory.  

trade-off is not the correct answer since it is a situation in which you accept losing something in return for benefits in other areas.

and finally, consequence is a general term used to accept what it comes when you make a decision. it can be a positive or negative consequence depending if the decision you took was the correct one.