I am being asked to identify and describe a real world example of an oligopoly. I chose the big American Automobile companies like GM, Ford, Toyota, Nissan, etc. I need help getting things started in answering the following questions.

What characteristics of this market fit the definition of an oligopoly?

What role does advertising play in this market?

Is this consistent with what you've learned about advertising and oligopoly in this course?

Thank you in advance!