Which of the Following Is Not a Reason Why Northerners

Which of the following is not a reason why northerners began to lose interest in black issues in the mid-1870s?

A) Economic troubles came up, including the serious Panic of 1873.
B) Some northern whites felt that they had done enough for blacks over the course of Reconstruction.
C) Blacks were generally happy with the results of the Enforcement Acts as well as the Thirteenth, Fourteenth, and Fifteenth Amendments. They thought they should be able to work things through on their own.
D) Actually, northerners continued to have a lot of interest in and focus on black issues, but southern racism was stronger.