Final answer:
Upton Sinclair meant that his book, The Jungle, accidentally drew attention to the unsanitary practices in the meatpacking industry rather than promoting Socialism.
Step-by-step explanation:
Upton Sinclair's quote, "I aimed at the public's heart, and by accident I hit it in the stomach," refers to the unintended consequences of his book, The Jungle. Sinclair wrote the novel to promote Socialism and expose the exploitation of workers in the meatpacking industry.
However, most readers focused more on the unsanitary practices in the industry, which led to the passing of the Federal Meat Inspection Act and the Pure Food and Drug Act in 1906. These regulations aimed at improving sanitation and protecting consumers, but they were not the intended political message of Sinclair's book.