After the assassination of Alexander II, his successor Nicholas II
a. Actively carried on Alexander's reforms
b. Was an even greater proponent of change and pushed for true democratic reform
c. Issued an edict that categorically declared the peasants to be serfs
d. Championed oppression and police control



Answer :

After the assassination of Alexander II, his successor Nicholas II "d. Championed oppression and police control," since he was believed to have been the most "radical" in terms of emerging policies.