The Jungle"a novel by Upton Sinclair about the meat packing industry of United States during the industrial revolution.

The Jungle. Giant industries had an enormous amount of control at the turn of the century in United States; the greed of the powerful ones has turned the American Dream into a nightmare for an ordinary worker. Idea of "Social Darwinism" was a very popular one at a time, it argued for government's noninterference in private economic affairs, "Social Darwinism" applied survival of the fittest to the economic atmosphere, which meant the rich are going …

…lesser-valued meaning. He is muckraker for opening the eyes of public onto the awfulness of American Industries, and he manages to get quite a response from the public. He is a propagandist for presenting a socialist model of society that he thinks would function much better in the industrial society. Sinclair directed this book to the public not only expose the filth of the industries but also a possible solution to the problem, hence socialism.