Some things started during roosevelts time as president that continue to be controversial

What would lead a historian to consider two events to have a relationship of correlation rather than causation?

What was martin luther king, jr., referencing in the passage that brought him to lead a protest in birmingham?

Prior to the presence of europeans on the continent, the slave trade in africa a) did not exist in any form. b) was limited to internal trade only. c) included the trans-saharan and indian ocean slave trade. d) was rarely needed due to the lack of an agricultural economy.