Answer:
B. Their Islamic sects differed on who the next Caliph would be.
Step-by-step explanation:
The Safavid Empire and the Ottoman Empire were both Islamic states, but they followed different branches of Islam. The Safavids were Shia Muslims, who believed that the successor of the Prophet Muhammad should be his cousin and son-in-law, Ali. The Ottomans were Sunni Muslims, who accepted the authority of the first four caliphs after Muhammad. The two sects had a long history of theological and political disputes, and often fought over the control of holy sites and regions. The Safavids and the Ottomans clashed several times in the 16th and 17th centuries, especially in the Caucasus and Mesopotamia. The conflict between the two empires was not only a religious one, but also a geopolitical one, as they competed for influence and resources in the Middle East and Central Asia.