What Significant Domestic Reform Did Tsar Alexander II Undertake in 1861

What significant domestic reform did Tsar Alexander II undertake in 1861?

A) He allowed Russian nobles to marry spouses from the middle class.
B) He increased the political power of landowners to place limits on the power of the monarchy.
C) He abolished serfdom, thereby freeing millions of people from virtual slavery.
D) He annulled the Greek Orthodox Church's jurisdiction over marriages.
E) He became a champion for social equality by agreeing to public education for all girls under age eight.