Why Did the Emancipation of Slaves Proceed Very Slowly in the Northern

Why did the emancipation of slaves proceed very slowly in the northern states during and after the Revolution?

A) The northern states gave priority to slaveholders' property rights so that emancipation often was spaced out over several slave generations.
B) Very few northerners saw any contradiction between extolling freedom for themselves and slavery for African Americans.
C) Slaves were threatening violence in the northern states,leading whites to retreat from their earlier support for emancipation.
D) Economically,slavery was becoming more viable and profitable in the North in the 1770s and early 1780s.