Answer:
B. The Kremlin is a fortress and symbol of power, C. Orthodox Christianity became the official religion.
Explanation:
Ivan the Terrible consolidated the Grand Duchy of Moscow, which gained total independence from Mongols. The Kremlin is a military and seat of the Tsar and the Russian Ortodox Christianity, which became the official religion of Russia until 1917.
The Russian peasants had less freedom than most European peasants, since rural economy was predominant and feudal institutions remained until Modern Age.
Ivan III accepted the Byzantine influence during his reign.