What was Vladimir, Grand Prince of Kiev, known for? A. After sending out men to investigate various religions, he chose Eastern Orthodox Christianity as the state religion. B. He defeated the Mongols and united the Russian princes under one rule. C. After abolishing the people's assembly, he took millions of acres of land from the nobles and gave it to those who were most loyal to him. D. He taxed his people heavily in order to build a magnificent palace and government complex in Moscow.