Which of the following best describes the main way that Upton Sinclair gathered research for The Jungle?

A. He hired investigators to spy on activities in a meat-packing plant.
B. He spent two years doing research in libraries all over America.
C. He went undercover as a worker in a meat-packing plant.
D. He interviewed experts in the meat-packing industry.

The main way that Upton Sinclair gathered research for The Jungle was by going undercover as a worker in a meat-packing plant. Through this firsthand experience, Sinclair was able to expose the unsanitary and dangerous working conditions in the meatpacking industry, which led to important reforms like the Meat Inspection Act and the Pure Food and Drug Act.

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