A muckraker is an investigative journalist or reporter who tries to expose corruption or societal issues in America. In this case, all of the people mentioned in the questions are considered muckrakers. For example, Jacob Riis wrote the book <em>How the Other Half Lives</em>. This book was about the poor living conditions in tenements in New York city. These tenements housed thousands of immigrants who lacked basic necessities in their homes.
