Answer:
D. Warring Arabian tribes became united.
Step-by-step explanation:
Shortly after Muhammad converted to Islam in Medina, and travelled to Mecca and other Arabian places to spread the world of Islam, Arabian tribes, who had been fighting each other for centuries, united and converted as well, forming a formidable religious and military force that would go on and conquer the rest of Middle East, North Africa, and even the Iberian Peninsula, in only a few decades.