Final answer:
The text from the Pact of Umar is most likely authored by the People of the Book, specifically Christians, who sought safe conduct from Caliph Umar in exchange for certain obligations.
Step-by-step explanation:
The group most likely to have authored this text from the Pact of Umar is the People of the Book, which refers to Christians and Jews. The text outlines a series of obligations that the Christians agreed to when seeking safe conduct from Caliph Umar, such as not building or repairing religious structures, not teaching the Quran to their children, and showing respect towards Muslims. These conditions reflect the status of Christians living under early Islamic rule and their acceptance of certain restrictions in exchange for protection.