Final answer:
The Russian princes in Moscow began two centuries of fighting the Mongols in the 14th century. After the fall of Kiev to the Mongols in 1240, Moscow emerged as a center of power and gained prominence.The correct option is A.
Step-by-step explanation:
The Russian princes in Moscow began two centuries of fighting the Mongols in the 14th century. After the fall of Kiev to the Mongols in 1240, Moscow emerged as a center of power and gained prominence. The Mongol presence in Russia, known as the Golden Horde, gradually lost its control, and in 1480, the Russian princes assembled a united army to defeat the Mongols.