One reason the fugitive slave act of 1850 angered northerners was that it a. gave states more power than the federal government. b. allowed states to arrest slave catchers for kidnapping. c. contradicted pre-existing personal liberty laws. d. required all citizens to support the slave system.

I think c is the answer but i'm not positive 

Your question: One reason the Fugitive Slave Act of 1850 angered Northerners was that it...?

 One reason the Fugitive Slave Act of 1850 angered Northerners was that it required all citizens to support the slave system.  

The Fugitive Slave act stated that even the Northerners, even though they didn't want to, had to help the Southerners or the slave catchers to catch slaves.  

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They hold a political party