The correct answer to this open question is the following.
The three power models in America are:
The Pluralist model.
This model of power establishes that there are certain kinds of groups that have similar interests and they associate to form groups of power that exert some control in society and politics and want to open more spaces to favor their particular interests.
So as there are many groups that have their own interests, but at the same time these interests are different from the other groups, then power is divided into different groups. They legally form political associations, unions, political groups that hire lobbyists and try to negotiate with legislators to make laws that favor their interests.
The Elite Theory.
This theory established that power in a nation relies on the hands of few groups of people that are wealthy enough that it can control most part of the decisions in politics and the economy.
This small group could be aristocrats, businessmen, or political families that have been exerting their control in the past in a quite discrete way. They do not like to appear in mass media or be acknowledged as the ones in power. They prefer to be the men behind the curtain, influence all the decisions.
Other theory such as the social theory or the Marxist Theory, establish that power should be in the hands of people and there has to be not only one source of power but different ones that help to balance power and decisions in a society. These theories favor the incursion of common citizens to the political spheres to make decisions that really took the people's needs into consideration.
