who found it necessary to use secret police?\nivan iii\nivan iv\nthe mongols\nthe vikings

who found it necessary to use secret police?\nivan iii\nivan iv\nthe mongols\nthe vikings
Answer
Brief Explanations:
Ivan IV (also known as Ivan the Terrible) established the Oprichnina, a secret police force, to suppress opposition and maintain control. Ivan III focused on unifying Russia, the Mongols had different governance methods, and the Vikings were raiders/settlers without such a secret police system.
Answer:
B. Ivan IV