Which book significantly changed laws and regulations for slaughterhouses?

The correct answer, "The Jungle," is significant because it is a powerful and influential novel written by Upton Sinclair, published in 1906. The book exposed the harsh conditions and exploitative practices within the meatpacking industry in Chicago, including unsanitary conditions in slaughterhouses. The vivid and often graphic descriptions of the treatment of animals, as well as the health risks to consumers, stirred public outrage and led to demands for reform. This response ultimately contributed to the passage of the Pure Food and Drug Act and the Meat Inspection Act in the same year, which established federal regulations for food safety and inspection of meat products. Therefore, the impact of "The Jungle" on food safety laws and the reform of slaughterhouses is well-documented and considerable.