The correct answer is D) agreeing not to end the slave trade at least for 20 years.
Northern and Southern states compromised on the slave trade by agreeing not to end the slave trade at least for 20 years.
During the North Carolina Ratifying Convention on July 26, 1788, a delegate asked why the first clause of the 9th section was going to be included in the Constitution. The reason was that some delegates from the North demanded the abolition of slavery immediately. But delegates from the South did not agree with that. The solicited that the federal government did not interfere with slave trade at all because trading of slaves was important for the economy of the Southern states. That is the reason why Northern and Southern states compromised on the slave trade by agreeing not to end the slave trade at least for 20 years.