Final answer:
The letter O represents how far Islam had spread by 732, a century after Muhammad's death.
Step-by-step explanation:
The letter O represents how far Islam had spread by 732, a century after Muhammad's death. By this time, Islam had spread throughout the Arabian Peninsula, Persia (now Iran), Egypt, Mesopotamia (now Iraq), and the eastern territories of the Byzantine Empire. It had also reached parts of Africa and Spain.
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