Concept:The second caliph, 'Umar, was the first to introduce a fixed stipend for public servants, including teachers.Explanation:As the Islamic state expanded, 'Umar organized state finances through the public treasury (Baitul Mal). He gave regular salaries to teachers and soldiers so they could carry out their duties faithfully. This stipend helped them support themselves and their families. This practice was not established by Abu Bakr, 'Uthman, or 'Ali.Answer:B. 'Umar