Answer: In a group of city-states, each city-state is independent and rules by its own king. No central power controlled all of the city-states. In an empire, consisting of a nation and the city-states and nations it has conquered, one ruler is in control.
Explanation: One has a king in where the other has just a ruler
(in the former Soviet Union) the policy or practice of restructuring or reforming the economic and political system.
By looking a the options I would say that the answer is A.
It was the results of the Mexican War.
