Why were some northemers against abolition?
oa) they felt the constitution prohibited slavery.
ob) they were afraid of the violence from abolitionists.
o c) they felt it would have positive effects on the northern economy.
od) they were afraid free african americans would take their jobs.

D) They were afraid free African Americans would take their jobs.

Explanation:

Though slavery had been abolished in the North, black Americans faced bigotry and discrimination in their every day life, in education, housing and regarding legal rights in northern states. Many poor white workers were afraid that if slaves from the South were liberated, they´d come massively to the North and take their jobs.  Other people were concerned abouth the stability of the Union. Rich merchants of the North believed their profits would fall if slavery was a abolished in the South.