The statement is true.
Step-by-step explanation:
The muckrakers were journalists that were focused on exposing the corruption among the high circles of the richest people, as well as giving real representations of the social and living conditions in the country. These journalists were very brave, as they didn't really had any protection or power to oppose the most powerful people in the country, but by using the freedom of speech they managed to get the people behind them, which is often the best protection.
While there were many news that were controversial and were never proven, there were also many that were proven and made a big blow to lot of rich people. Lot of people ended up in courts and later in prison, or were forced to pay huge compensations, having their reputation destroyed, and being pushed aside by the people.