Answer:
The correct answer is "gold".
Step-by-step explanation:
Ghana and Mali were two of the most notorious empires of West Africa during pre-colonial times. The wealth of these two empires lied largely on the abundance of the natural resource of gold in these territories. Ghana and Mali profited mostly from the trans-Saharan gold trade, selling their gold to distant merchants through Berbers that utilized camels that carry large loads of the product.