@prpinrni,
None of these, actually.
Congress added a section to the Missouri Compromise that made California a free state. Southerners only agreed to this because Northerners agreed to make Utah and New Mexico territories open to slavery, AND to pass the Fugitive Slave Act (which would require Northerners to return escaped slaves to their slave owners in the South).
Out of A - D, I guess B is the closest, as the Southerns had a problem with a new free state admission and demanded concessions in order to go along with it. Definitely not A. Definitely not D.