Although It Would Prove to Be a Long and Uneven

Although it would prove to be a long and uneven process,the abolition of slavery was begun in the modern world with the:

A) ratification of the U.S.Constitution.
B) abolishment of serfdom by Germany.
C) adoption of the Declaration of the Rights of Man and the Citizen.
D) Haitian Revolution against Napoleonic France.
E) British abolishment of slavery within their empire.