Most blacks who held elected office in southern states during Reconstruction A. Had moved from the North to take advantage of the situation. B. Were independent and difficult for radical Republicans to influence. C. Were illiterate former slaves. D. Had been free in the prewar period.

Most blacks who held elected office in southern states during Reconstruction: D. Had been free in the prewar period.

Explanation:

During Reconstructon, many black leaders had been freed before de Civil War. Some of them had worked as artesans or had been parto of the Union Army.

The slaves would freed themselves in few cases by self-purchase or when ther owner would die.    

b or c im pretty sure