Final answer:
Trade during the medieval period in West Africa led to the building of great empires like the kingdom of Ghana and enhanced cultural diffusion, resulting in a diverse population.
Step-by-step explanation:
During the medieval period, trade in West Africa played a crucial role in the development of strong states like the kingdom of Ghana. This trade, especially in gold and salt, not only led to the creation of great empires but also fostered significant cultural diversity through increased cultural diffusion. Camels were key in connecting West Africa with North Africa, the Middle East, and Europe, creating a vast network that was instrumental in these exchanges. The correct answer to the question is: a. Trade led to the building of great empires and also increased cultural diffusion, leading to a diverse population.