A. is a period unified by a common theme, often social or political

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Explanation:

An era is a period unified by a common theme, often social or political. This can often be confused with a period, but it should be noted that an era is harder to define in terms of the various social elements of which it is comprised. 

two months after his defeat of napoleon bonaparte's colonial forces, jean-jacques dessalines proclaims the independence of saint-domingue, renaming it haiti after its original arawak name. in 1791, a slave revolt erupted on the french colony, and toussaint-louverture, a former slave, took control of the rebels.

true

coz they had the rank system in society according to the economic power of the people