The correct answer is A)The Ottomans were Sunni, and the Safavids were Shia.
A key difference between the Ottomans and the Safavids was that the Ottomans were Sunni, and the Safavids were Shia.
Both, the Ottoman Empire and the Safavid Empire were superpowers in West Asia and the major empires of its time in the region. They had many differences, but the most critical was based on religion. They continually fight each other. And the last major war between the two was the Safavid-Ottoman War of 1623 that ended in 1639, trying to gain total control of the territory of Sumeria-Mesopotamia.