An oligopoly is a market structure in which the market is shared between a few firms, this few firms sell identical or differentiated products , and the industry has significant barriers to entry.
The automobile industry considered an oligopoly because there are few leading auto manufacturers which are having significant influence over the industry. All these firms sell identical products. And the last characteristic of an oligopoly is also there: it is very hard for a firm to entry this market because production costs are huge.
The United States is a representative democracy by the idea that, as the 'Declaration of Independence' states,"We the People...", a representative democracy brings about the direct idea of the people. Thus, the people vote in an intricate system for representatives of states (of those in the states), city mayors, and well...the President!
Dana (30) most likely due to people becoming more stable in "Mid-Life," A range from around 25-45. It starts to become unstable around 50, so my guess would be Dana (30)
