Why Did the Acquisition of Texas,New Mexico,and California Cause Conflict

Why did the acquisition of Texas,New Mexico,and California cause conflict in the United States?

A) The Constitution did not establish the status of slavery in future states, so whether or not those territories would allow slavery was hotly debated.
B) The new territories were all north of the Missouri Compromise line, which threatened to disrupt the balance between slave and free states.
C) The Missouri Compromise mandated that those territories should be free, but the economies of the territories were already completely dependent on slavery.
D) Mexico kept claiming the territories even after they had been annexed to the United States.
E) Citizens in those territories refused to pay taxes to a federal government that they did not support.