How did the united states’ new western territories increase tensions between the north and south?

a.
the new territories reduced the north's dependency on the south for cotton and other raw materials.
b.
the north wanted the new territories to be free states, while the south wanted them to be slave states.
c.
the south was against the expansion of the united states territory beyond the rio grande.
d.
the cost of gaining new territories in war harmed the south because its smaller economy couldn’t afford it.