Explanation:

- Elton Mayo

- Known for the Hawthorne Studies.

- Focused on human relations and motivation in the workplace.

- Karl Marx

- Philosopher and economist.

- Theorized class struggle and capitalism's impact on labor.

- John Dunlop

- Developed the Systems Theory of Industrial Relations.

- Viewed industrial relations as a subsystem within society.

- Roethlisberger

- Worked on the Hawthorne Studies.

- Collaborated with Mayo on human behavior research.

- Correct Answer: John Dunlop

- Provided a framework for understanding industrial relations.

- Emphasized the interaction of management, labor, and government.