What was not examined by the investigative journalists in the late nineteenth and early twentieth centuries?

a. John D. Rockefeller's corrupt practices at Standard Oil

b. violations in the meatpacking industry

c. long hours required of sharecropping farmers

d. brutal working conditions in mines and on railroads

c. long hours required of sharecropping farmers.

The investigative journalists in the late nineteenth and early twentieth centuries examined many different issues. However, one area that was not extensively examined by these journalists was option c. The long hours required of sharecropping farmers. While journalists did investigate and expose various social and economic injustices, such as John D. Rockefeller's corrupt practices at Standard Oil (option a), violations in the meatpacking industry (option b), and brutal working conditions in mines and on railroads (option d), the specific issue of long hours required of sharecropping farmers received less attention during this period.