Question

what does the rise of white extremist groups like the kkk suggest about the limits of federal authority during reconstruction?
the supreme court supported extremist organizations.
congress refused to pass laws against domestic terrorism.
southern states fully cooperated with reconstruction policies.
the federal government struggled to enforce civil rights legislation.

Explanation:

During Reconstruction, despite federal civil - rights legislation, white extremist groups like the KKK emerged. This indicates that the federal government had difficulties in effectively implementing these laws. The Supreme Court did not support extremist organizations (it actually weakened some Reconstruction - era laws in a different sense). Congress did pass laws against such activities (e.g., the Enforcement Acts). Southern states did not fully cooperate with Reconstruction policies (they resisted through various means including supporting groups like the KKK).

Answer:

The federal government struggled to enforce civil rights legislation.