Louisiana purchase, october 20, 1803
They were formed to resist new British taxes
The correct answer is Austria-Hungary
Nationalism started rising after numerous years of wars during the 19th century. Austria-Hungary believed that it had the right to be the great empire that it used to be and that it partially was at the moment. That's why things like world war 1 happened since countries wanted to establish themselves as great.
An important Roman contribution to American government is the idea of a "republic" or the creation of a representative democracy. In the Roman Republic, representatives were elected by the people to govern on their behalf in the Senate, similar principles were used in structuring the American system of government.