Why might the soviet government have persecuted the russian orthodox church ?

Christianity entered Russia from Byzantium. In the year 988, Prince Vladimir was baptized in the River Dnieper, with all the inhabitants of Kiev, and the pagan statues were destroyed. Thus was born the Russian Orthodox Church, and thus Byzantine theology, liturgical forms and church-state relationships were established as basic characteristics of popular religion in Russia. Since this missionary enterprise took place at the height of the quarrel between the Patriarch of the East and the Pope of the West, the Russian Church and people inherited the Eastern Church's antagonism to Rome and the West and shared its isolation from the Renaissance, the Reformation and the rise of modern concepts of social Christianity. Instead, the Russian Orthodox Church entered the twentieth century with the religious outlook developed no later than the Seventh Ecumenical Council, held in 787.

answer; i believe that the correct answer is (d); //declaration of independence; plz check first good luck