Which of the Following Is True Regarding Congress and the African

Which of the following is true regarding Congress and the African slave trade in the United States under the Constitution?

A) Congress never prohibited this slave trade.
B) The First Congress under the Constitution prohibited the importation of slaves into the United States.
C) Congress always let individual states make their own decisions with regard to importing slaves.
D) Congress prohibited the African slave trade twenty years after ratification of the Constitution.