The example of an ancient Arabian state that traded extensively and controlled territories on the East African coast can best be used as evidence of "the long-term continuities in state-building in coastal East Africa."
This is because long-term state-building involves trade relations and commerce, among others, such as politics and economics.
Thus, information of extended trades between the Arabian state and the East African coast shows long-term state-building between the two regions.
Hence, in this case, it is concluded that the correct answer is option B. "the long-term continuities in state-building in coastal East Africa."
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D). Vast empires.
Classical civilizations developed vast empires, whereas early river valley civilizations did not.
