Final answer:
The Great Gatsby explores the topic of commercialism, particularly the illegal sale of alcohol in the 1920s.
Step-by-step explanation:
According to Rothman, one of the central topics that The Great Gatsby explores is commercialism, specifically the illegal sale of alcohol in the 1920s. The novel portrays the culture of excess and material success that characterized the Roaring Twenties, with characters like Gatsby engaging in the illegal liquor trade to accumulate wealth.