Why were early unions for skilled workers only

Plz which of the following statements about the fugitive slave act of 1850 is not accurate? a. marshals you refuse to arrest a suspected fugitive could be find $1000. b. slave owners had to present evidence an african-american in the north was a fugitive slave. c. any person who provided food or shelter to a fugitive slave could be find $1000 and placed in jail for six months. d. it required of federal marshals to arrest any african-american suspected of being a runaway slave.