The plantation bosses who kept the enslaved Africans working hard were called A. overseers B. slaveholders C. supervisors D. employers

The word you are looking for is Overseers.

slave owners were the people who actually owned the slaves. employers had nothing to do with slavery per say that was just what they were in a business term, supervisors although much the same was not what these particular people were called.

The plantation bosses who kept enslaved Africans working hard were called overseers.