The abolition movement, which began in the northern states, was sparked during which event?

Though slavery was now abolished in the late 1700s in the Northern states while the Southern states were still practicing slavery.  The abolition movement began through the efforts of William Lloyd Garrison, Frederick Douglas, Harriet Beecher Stowe  and other prominent proponents of abolition who believed that slavery was a crime.

yes i can of course like what is it gonna be about

austria

hugary

yugoslavia

czechoslovakia