“What part of the Middle West?” I inquired casually.
Nick notices that Gatsby has clearly been lying about what he claims to be his past. Gatsby takes no notice of the gap in his own response, as San Francisco is part of the west coast, not the Middle West. If he really were “the son of some wealthy people” there, doubtlessly, he would know where San Francisco is located (and he’s probably not good at geography neither). As Nick finds out that Gatsby lied about his parents, Gatsby’s whole argument consequently falls into pieces and is left dubious.
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