The correct answer is D. Elton Mayo.
Elton Mayo was an Australian-born 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’s work had a profound impact on the field of organizational behavior, and he is considered one of the founders of the human relations movement.
Mary Parker Follett was an American political scientist, philosopher, and management consultant. She is considered one of the founders of the field of organizational behavior, and her work has been influential in the fields of management, leadership, and conflict resolution.
Lillian Gilbreth was an American industrial engineer and efficiency expert. She is best known for her work with her husband, Frank Gilbreth, on the study of motion and time study. Lillian Gilbreth was also a pioneer in the field of human factors engineering.
Henry Fayol was a French mining engineer and business executive. He is considered one of the founders of modern management theory. Fayol’s work is best known for his 14 principles of management, which are still widely used today.
In conclusion, the correct answer to the question “Pioneer of Human Relations is” is D. Elton Mayo.