Who was Ida B. Wells known for advocating against?

Ida B. Wells is best known for her vigorous advocacy against lynching, making her a key figure in the anti-lynching movement in the late 19th and early 20th centuries. She utilized her platform as a journalist to expose the brutal realities of lynching and the societal complacency surrounding it. Her investigative reporting, particularly her pamphlet "Southern Horrors: Lynch Law in All Its Phases," highlighted the racial violence faced by African Americans, revealing the truth behind the justifications often given for such acts. This work not only aimed to inform the public but also sought to mobilize people to take action against these injustices, ultimately contributing to the broader civil rights movement. Therefore, her fight against lynching is central to her legacy, making this the correct answer.