By the mid-1800s, most enslaved people in the American south A. Worked as domestic servants
B. Lived on large plantations

Honestly they are both correct. They did live on large agricultural plantations as horse servants or field hands. They also were house servants. Most enslaves women worked as domestic servants and most enslaved men worked on the plantation. But; looking at this question they are mainly asking where enslaved people in the American south lived not what they did. So the answer would be, B- Lived on large plantations.

Explanation:

In the early 19th century, most enslaved men and women worked on large agricultural plantations, as house servants, or field hands. Life for the  enslaved  was brutal; they were subject to repression, harsh punishments, and strict racial policing.

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