Read the list and answer the question. Economy of West African Empires The empires of Ghana, Mali, and Songhai thrived on the wealth of gold. Cities were established for trade of gold and salt. Timbuktu became an economic and cultural center. Which conclusion is best supported by the list? A. African rulers limited the manufacture of finished goods. B. Trans-Saharan trade routes helped maintain regional commerce. C. African rulers limited trade with overseas nations. D. Trans-Saharan trade routes were controlled by nomadic warlords.