Final answer:
Strong African states and diseases in the African interior limited European colonization to coastal trading forts.
Step-by-step explanation:
The best assertion that accounts for the limited colonization of Africa by Europeans before the 19th century, compared to the Americas, is: B. Strong African states and diseases in the African interior limited European colonization to coastal trading forts.
Unlike the Americas where European colonization led to large-scale settlement and exploitation, Africa's strong states and geographical challenges such as diseases and difficult terrains hindered thorough European penetration. Instead, Europeans established coastal trading forts in Africa to facilitate trade without extensive colonization.
For example, the Portuguese built trading forts like Elmina Castle on the Gold Coast of present-day Ghana, which served as a center for the transatlantic slave trade but did not result in widespread European settlement.
Learn more about European colonization of Africa