Why Was the Missouri Compromise the Beginning, Rather Than the End

Why was the Missouri Compromise the beginning, rather than the end, of the sectional debate over slavery?

A) The Compromise was only a temporary solution because it left open the question of how the balance between free and slave states would be maintained.
B) The Compromise left all of the Louisiana Territory open to slavery, and it greatly disappointed Northerners, who set out to eradicate slavery altogether.
C) By banning slavery anywhere west of the Mississippi River, the Compromise left many Southerners convinced that their only solution was to industrialize the South and abandon slavery.
D) Henry Clay bitterly regretted his role in the Compromise and dedicated the rest of his career to the defense and extension of slavery.