He 13th 14th and 15th Amendments to the Constitution were undermined by all of the following EXCEPT?

The 13th, 14th, and 15th Amendments, which aimed to establish civil rights for formerly enslaved individuals, were undermined by various discriminatory practices such as Jim Crow laws, Black Codes, and systemic racism. However, they were not undermined by the establishment of the Freedmen's Bureau, which was created to assist newly freed slaves in their transition to freedom and provide support in education, employment, and legal matters.