The correct answer is A. Barnard.
Chester I. Barnard was an American economist, political scientist, and sociologist, who is considered one of the most influential theorists of organization and management. In his 1938 book The Functions of the Executive, Barnard defined authority as “the character of a communication in an organization by virtue of which it is accepted by a group as governing the actions of its members.” He argued that authority is not a property of a person or position, but rather a relationship that is created when a person accepts the orders of another.
Fayol, Strong, and Louise Allen are all other theorists who have written about authority, but their definitions are not as widely accepted as Barnard’s. Fayol defined authority as “the right to give orders and the power to exact obedience.” Strong defined authority as “the power to influence the behavior of others.” Louise Allen defined authority as “the right to make decisions and the power to enforce those decisions.”
Barnard’s definition of authority is more nuanced than the others, and it takes into account the fact that authority is a relationship that is created between two or more people. Fayol, Strong, and Louise Allen’s definitions are more simplistic, and they do not take into account the fact that authority can be accepted or rejected.