What is the final answer to the main question of The Great Gatsby?
There are 3 partial answers to that question and one final one. Please describe each of these, who gave them, and how believable each one is.
While I am not sure as to the partial answers to which you allude, I will try to address the question as to what are the final answers revealed to us in The Great Gatsby. I think that the lasting answer given to us in Fitzgerald's work is the illusion of happiness present in the 1920's. This particular age was one built upon the premise of mass consumption, widespread consumerism, the belief that the more money one had the "better" they were, and the fixation on the celebrity. This particular age had spawned an unparalleled optimism in American society and emergence of faith in modern growth and development. Fitzgerald's work casts a large and looming shadow over all of it. In this particular setting, there are few that are immune from his criticism. The answers the work reveals to us is that money and character can exist in two different realms: the worst of people in the novel are the most wealthy and use their wealth as a method to shield themselves from the pressing realities of ethical, emotional, and moral responsibility. They also cast a great deal of doubt into American obsession with celebrity, a theme that has been reverberated over time with the cautionary tales of celebrities. Finally, the book addresses the issue of inaction, and the results of "waiting" for something we know in our hearts that will never arrive. Nick seems to be "waiting" for something, anything and only the murder of Gatsby gets him to take action. For his part, Gatsby waits, almost waiting to be killed. Tom, Daisy, and Jordan are waiting for the next party or the next scandal that can serve as fodder for party gossip. The book is a fitting statement to cast Fitzgerald's "Jazz Age" into a more critical and skeptical light. The lessons learned from the book, while not immediately appreciated at the time, have reverberated throughout American history since, like an inescapable echo in a darkened cave.