What Was the Muckraker Tradition

What was the muckraker tradition?

A) Conservative journalism in the late nineteenth and early twentieth centuries that was blatantly anti-labor
B) Liberal journalism in the late nineteenth and early twentieth centuries that was openly anti-business
C) Progressive journalism of the late nineteenth and early twentieth centuries that was dedicated to uncovering political and corporate corruption
D) Socialistic journalism of the late nineteenth and early twentieth centuries that was dedicated to uncovering the exploitation of the proletariat by the bourgeoisie