Which of these could not have occurred until the postclassical era?

a. a byzantine merchant sells goods in india,

b. a persian general decides to attack a greek city-state.

c. a chinese ruler sends an ambassador to europe,

d. a west african ruler converts to islam.

A West African ruler converts to Islam.

Option D

Explanation:

The post classical era marked expansion of civilizations and development of trade. International trade developed even beyond Silk Road expanding to Europe, Africa, Asia. Islam started spreading based on the revelation of prophet Muhammad in the Arabian Peninsula. Islam had a reflection of Jews, Christians and Zoroastrians. Islam started spreading widely in Africa, Europe and Asia due to invasions, expansions, merchants and trade activities. Africa was the first continent to be converted to Islam. Almost one third of the Muslims are in this continent.