Question

What natural advantage did the kingdoms of West Africa have? 

Answer 1

One natural advantage that the kingdoms of West Africa had was "B. An abundance of natural resources including salt and gold," which is why it became such a popular trading area. 

Answer 2

Answer;
The natural advantage the kingdoms of West Africa had was an abundance of natural resources including salt and gold.

Explanation; 
The major advantage of the West Africa kingdom was abundance of resources such as gold and salt, in addition the trans-Saharan trade played a great role. 
These kingdoms acquired wealth through control of the gold trade in the region. Salt  was valuable to western Africans for replenishing the body, preserving food, and its good taste.