Final answer:
The growth of trade in West Africa facilitated the spread of Islam as merchants and traders carried the ideas of Islam along the trans-Saharan trade routes. Islam was adopted by ruling sub-Saharan African elites and blended with traditional beliefs. The option (B) is correct.
Step-by-step explanation:
The growth of trade in West Africa had a significant impact on Islam. As trade networks expanded, Islam spread throughout the region, facilitated by merchants, traders, scholars, and missionaries. Muslim Berbers carried the ideas of Islam from North Africa along the trans-Saharan trade routes and influenced West African trading towns.
The adoption of Islam was also encouraged by local states for economic benefits and access to new ideas and technologies. Local states recognized the economic benefits of trade and encouraged the spread of Islam. Therefore, option (B) is correct.