The correct answer is C) overseers.
Supervisors who were in charge of enslaved field workers and often treated them cruelly were called overseers.
The overseers in the time of large plantations in the Southern states, were young men that worked for the landowners. Their task was simply to check that the slaves were doing all the hard work to the best of their capabilities. Small plantations did not required overseers, but in the large ones, it was a necessity.