Answer:
B. Diverse multiple languages, religions, and forms of government
Explanation:
Even though it's true that African people were hard hit by bubonic plague, this happened in 14th century. Not Africa in early modern period. This is why option A is wrong.
African was not cut-off from international trade. They established a good trading relationship with a lot of western countries (Superficially for Precious Stones, minerals, and fruits commodities.) This is why option B is wrong.
The vast majority of countries in African continent was run as a republic, not an empire. They are led by presidents and conduct their own election regularly just like most countries in the world. This is why option D is wrong.
