Upton Sinclair, Frank Norris and Ida Tarbell made their greatest contributions to the Progressive movement by (4) publishing books and articles to expose the problems of society. Upton Sinclair wrote a book which showed the dangerous and unsanitary lives workers of the Meatpacking District went through on a daily basis, Frank Norris exposed the struggle railroad workers go through with their bosses and the unfairness of the railroad workers life in California and Ida Tarbell wrote about the manipulative men behind the oil trade.
I believe the answer is D: <span>the treatment of slaves by their owners
Hope I helped! :)</span>
The farmers of northern alliance wanted a natural alliance to include African American members. It was a financial movement which came into existence in 1875. The farmers of the United States of America were part of this movement and several other political organizations also involve themselves in this organization.
The reason behind this movement was to abolish or end the negative effects of crop-lien system (a credit system) on farmers in the period after the American Civil War and save the rights of the American farmers.
