Which was the main group/person that did not want to re-admit Southern states into the Union?
Andrew Johnson
Abraham Lincoln
Radical Republicans
Dynamic Democrats

C. Radical Republicans

Explanation: The Democrats and Republicans switched parties. This means at the time, it was Democrats who wanted slavery and Republicans were against it. Republicans even proposed the 14th amendment before the Southern States were readmitted. I hope this is correct :) (If not, please let me know)

The answer would be a