Final answer:
Islam is the predominant religion in Northern Africa, having rapidly expanded there in the early centuries of its existence and becoming the dominant religious and cultural force by 1200.
Step-by-step explanation:
The predominant religion in Northern Africa is Islam. Over the centuries, Islam spread rapidly from its birthplace on the Arabian Peninsula into North Africa, forming one of the bedrocks of the region's culture and society. This began in the seventh and eighth centuries when Islamic armies consolidated control and established settlements that grew into cities under the Islamic Caliphate. As a result, by 1200, Islam became the dominant religion across North Africa and other regions such as the Middle East, parts of South Asia, and even the Iberian Peninsula before Christian re-conquest. Therefore, in the options provided, A. Northern Africa is the correct answer where Islam is the predominant religion.