The central disagreement after Muhammad's death concerned who should be his successor.

• A. Umar and Uthman
• B. Hassan and Hussein
• C. Abu Bakr or Ali
• D. Ali and Muawiyah

Answer: (C)

After Muhammad's death, the crucial issue was who should lead the Muslim community. Muhammad did not leave a clear, universally accepted successor, so leadership became a question of legitimacy and method. One view favored Abu Bakr, a trusted companion and Muhammad’s father-in-law, who was chosen by a small group of senior Muslims through consultation and became the first caliph. The other view favored Ali, Muhammad’s cousin and son-in-law, whom many believed was the rightful successor due to kinship and close proximity to the Prophet; this view is central to Shia tradition, which holds Ali as the first Imam. This disagreement over who could legitimately succeed Muhammad underpins the later Sunni–Shia split. The other names reference later caliphs or relatives involved in subsequent power struggles, but the immediate dispute was between Abu Bakr and Ali.