When did the kingdoms of ghana and mali flourish?
a. 100 - 400, during the era when christianity was founded and organized
b. 400 - 1400, during the era when the roman empire declined, the byzantine empire flourished, and islam was founded
c. 700 - 1200, during the era when islam was founded and the muslim empire spread
d. 1100 - 1600, when the middle ages ended and kings assumed great power in western europe