Answer: A. In the postclassical era, the world's most powerful states were in in Asia and the Middle East. In the modern era, power shifted to Eurasia.
Explanation:
During the Post-Classical era (600 CE to 1450 CE), areas previously under control of the Empires underwent an economic decline. The fall of Rome brought new possibilities in the Middle East, and Arabs regain control over areas under Roman rule.
During the Early Modern (1450-1750) and the Modern era (1750-1900), Eurasia had the most powerful states, changing the power distribution.
