The correct answer is A. Elton Mayo.
Elton Mayo was an Australian-born American psychologist, sociologist, and pioneering theorist of management. He is best known for his work in the Hawthorne Studies, which demonstrated the importance of social interactions to workplace productivity. Mayo concluded that the factory was a social system and informal groups at work place playa vital role in industrial affairs.
Henry Fayol was a French mining engineer and business executive who developed a general theory of business administration that is often called Fayolism. Fayol’s theory of management emphasized the importance of planning, organizing, commanding, coordinating, and controlling.
Robert Blake and Jane Mouton were American social scientists who developed the Managerial Grid, a leadership style model. The Managerial Grid is based on two dimensions: concern for production and concern for people.
Frederick Herzberg was an American psychologist who developed the Two-Factor Theory of Motivation. The Two-Factor Theory of Motivation states that there are two sets of factors that motivate employees: hygiene factors and motivators. Hygiene factors are extrinsic factors that prevent dissatisfaction, such as pay, working conditions, and job security. Motivators are intrinsic factors that lead to satisfaction, such as achievement, recognition, and responsibility.