Final answer:
W.E.B. Du Bois is the individual who contributed to the Niagara Movement and advocated for a more activist approach to achieving justice.
Step-by-step explanation:
The individual who contributed to the Niagara Movement and advocated for a more activist approach to discuss justice is W.E.B. Du Bois (C). Du Bois was a notable figure in the fight for African American civil rights who believed in immediate political, economic, and social equality for African Americans. He criticized Booker T. Washington's more accommodating strategies towards racism and instead led the establishment of the Niagara Movement in 1905, calling for full civil liberties and an end to discrimination. Du Bois continued his efforts as a key leader in the creation of the National Association for the Advancement of Colored People (NAACP) and served as its director of publications for many years.