Answer:
Upton Sinclair:
Title of Work: "The Jungle" (1906)
Notable Contribution: "The Jungle" exposed the unsanitary and often horrifying conditions in the meatpacking industry, leading to significant public outcry and eventually the passage of the Pure Food and Drug Act and the Meat Inspection Act in 1906.
Ida Tarbell:
Title of Work: "The History of the Standard Oil Company" (1904)
Notable Contribution: Ida Tarbell's investigation into the practices of the Standard Oil Company revealed monopolistic and anti-competitive actions. Her work contributed to the eventual breakup of the Standard Oil trust by the Supreme Court in 1911.