The best explanation for the change in the population of enslaved Africans from 1601 to 1800 is:
(Choice D) Enslaved Africans performed agricultural labor in the West Indies and the Southern and Chesapeake colonies.
This choice accurately reflects the primary role of enslaved Africans in the economy of these regions, particularly in the production of cash crops like sugar, tobacco, and rice, which drove the demand for enslaved labor.