Concept: The need to preserve the Qur'an arose after many of its memorizers were killed in battle.Explanation: During the Riddah wars, a large number of the companions who had memorized the entire Qur'an were martyred.This created a real danger that a major portion of the revealed text could be lost permanently.To protect the Qur'an from being lost, Caliph Abu Bakr ordered its compilation into a single written manuscript.Therefore, the primary reason for compiling the Qur'an was the deaths of many memorizers in the Riddah wars.Answer: C. many memorizers of the Qur'an did in Riddah wars