Answer:
B- Twenty years after ratification of the Constitution, the slave trade would be prohibited.
Step-by-step explanation:
The Constitutional Convention held in 1787 was never initially with the aim of changing the constitution of US but was secretly agreed to by the 55 delegate sent by some of the States. In the convention, series of agreements were reached ranging from the legislature, the electoral process and voting strength of each states to the slaves.
Series of compromises where made in each of the issue raised. For the Slave trading, the compromise was that, after 20 years (exactly on year 1808), slave trade will be prohibited across the country.