The correct answer is C.
The contrast created between East Egg and West Egg suggest that the story’s conflict will be based on wealth and appearances.
The East Egg is the area of "old money," people who has inherited all of their money and are accustomed to a certain standard of living.
On the other side, the West Egg is inhabited by "new money," people who has recently amassed wealth and wishes to show their new social status.
This contrast is used during the novel to expose the theme of appearences and wealth: how people want to show themselves as something they are not. And how they wish to get the approval of others, even if that means being unhappy and untrue to themselves.
