What business does Gatsby tell Nick and Daisy he was in?

In chapter five while Gatsby and Nick wait for Daisy outside Nick's bungalow prior to touring Gatsby's house, Gatsby casually observes "It took me just three years to earn the money that bought it."  Realizing that he has contradicted his earlier claim that he had inherited his wealth, he quickly tells Nick "I was in the drug business and then I was in the oil business."  

In chapter six, Daisy tells Tom that Gatsby...

In chapter five while Gatsby and Nick wait for Daisy outside Nick's bungalow prior to touring Gatsby's house, Gatsby casually observes "It took me just three years to earn the money that bought it."  Realizing that he has contradicted his earlier claim that he had inherited his wealth, he quickly tells Nick "I was in the drug business and then I was in the oil business."  

In chapter six, Daisy tells Tom that Gatsby "owned some drug-stores, a lot of drug-stores. He built them up himself." Readers assume that Gatsby has told her this in private, since Nick, the novel's narrator, does not witness the conversation and Daisy does not hear Gatsby's remarks in chapter five.

When Tom confronts Gatsby in chapter seven, he reveals to Daisy, Nick, and Jordan that a private investigator he has hired has discovered that Gatsby and Meyer Wolfsheim had bought drug-stores in Chicago "and sold grain alcohol over the counter."  Gatsby does not deny bootlegging.   

Fitzgerald, F. Scott. The Great Gatsby.  Charles Scribner's Sons, 1925.