The correct answer is A.
The location of F. Scott Fitzgerald's "The Great Gatsby" is important because it emphasizes the decadence of the 1920's.
This time, known as the "roaring twenties" was a period of social and political change. America's wealth doubled, which led to a consumer society. It is often related with pleasure seeking and people having a good time after the devastation of the First World War.
Concepts such as hypocrisy, fakeness of character, and lavish use of wealth in The Great Gatsby come from the ideals of the Roaring Twenties. Fitzgerald used them in his novel to criticize the corrpution and decadence of America during this era.