What were the major reasons for the sunni-shia split in the islamic umma?

The issue of succession

Explanation:

The split between Sunnis and Shiites occurred in 632, after the death of prophet Mohammad. It  was because of the dispute among the Muslims of Saudi Arabia about the issue of succession. Prophets followers wanted the community to decide the successor while some believed that one of his family members should become the leader. Shia were the ones who belied that the leadership should stay within the prophet's family and supported Ali, his son-in-law. While the Sunnis wanted a person who was  accepted by the elite community. It was due to this political division that Sunni-Shia Split occurred.

answer; ///i believe that the correct answer is (b); ///the candidate must be a native born american citzen;

the right choice would be a. culture within the city-state. c. loyalty to the police. d separation by land and sea.