Which of the following inferences is most supported by the discussion of copper and gold in the passage?

(A) Mali was able to forge advanced bronze tools from its mineral resources. (B) International trade with Sub-Saharan Africa involved the exchange of mineral resources. (C) The jizya could only be collected on unbelievers who had minerals to exploit. (D) Mali’s relatively advanced mining technologies accounted for its mineral wealth.Explanation: The discussion of copper and gold is in the middle of the passage in which Mansa Musa claims that Mali sells copper for gold. Choices (A), (C), and (D) do not mention trade in any way, so they can be eliminated for this reason. Choice (B) is correct.