Final answer:
The growing difference between the slave population in the North and South after 1650 can be best explained by the economic differences between the two regions.
Step-by-step explanation:
The growing difference between the slave population in the North and South after 1650 can be best explained by the economic differences between the two regions. The Southern economy became increasingly dependent on large-scale farming, particularly the production of cotton, which relied heavily on slave labor. This led to a significant increase in the number of slaves in the South.
In contrast, the North had a larger population and a more diverse economy that relied less on slavery. Therefore, option D, The Southern economy became increasingly dependent on large-scale farming, best explains the growing difference between the slave populations in the North and South.