Which choice fits in the blank in this Progressive Era timeline? A) 1903- Helen Hunt Jackson publishes regarding treatment of Native Americans B) 1906- Upton Sinclair publishes The Jungle, criticizing the working conditions in the U.S. meat processing industry C) 1912- Theodore Roosevelt Publishes The Square Deal in which he addresses problems in the treatment of American unions D) 1912- Sir Arthur Conan Doyle publishes The Lost World showing the deforestation of the rain forests.