The correct answer is C. Immorality leads to suffering.
Within the novel, the theme of immorality and suffering can be seen most clearly in the case of Gatsby, Daisy, and Tom. Daisy and Tom are married, but are not in love with each other. Tom is cheating on Daisy with Myrtle (she died in an accident), Daisy is cheating on Tom with Gatsby (Gatsby dies after he is killed by Myrtle's wife), and nobody is happy in the end thanks to their immorality.
