The statement that best explains the causes leading to the emancipation of Russia’s serfs is:
"Alexander II saw serfdom as inhumane, and the military loss in the Crimean War prompted Alexander II to enact social reform, which led to the emancipation of Russia’s serfs."
This statement captures both the moral perspective of Alexander II regarding serfdom and the practical considerations from the military defeat, highlighting the impetus for reform that culminated in the Emancipation Reform of 1861.