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.

i thinl it is the 1st answer

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.