Why is Upton Sinclair responsible for the government passing the Pure Food and Drug Act?

The Jungle by Upton Sinclair, with its graphic and revolting descriptions of unsanitary conditions and unscrupulous practices rampant in the meatpacking industry, was an inspirational piece that kept the public's attention on the important issue of unhygienic meat processing plants that later led to food inspection 

sadly i believe the answer is d