What definition best fits the term muckraker?

The Muckrakers were a group of investigative reporters who did award-winning stories that exposed corrupt business practices in the early 1900s. Among them were Ida Tarbell, Upton Sinclair, and Lincoln Steffens. Most wrote for magazines, but several also wrote books or newspaper articles. Their name referred to their willingness to get down in the muck (the dirt) to extract important information and find the truth that the public needed to know.