Answer:
They were reform - minded journalists.
Explanation:
Muckrakers were exposing some sord of political, child labor, workers safety issues and that's the main reason why they had impact on American life. As reform - minded journalists they were investigative reporters and they were writing all about their investigation.
Muckrakers were attractive in Progressive Era (1890-1920). Nowadays, we can find some Muckraker articles. In these articles we can find stories about corruption and wealthy businessmen.
Some of the Muckrakers were: John Spargo, Lincoln Steffens, Ida Wells, Upton Sincilar, Jacob Riis...
They risked their lives by writing those kinds of articles but they did bring improvements.