The correct answer is: Awareness of the importance of group dynamics and worker attitudes as an influence on productivity

Rationale: 'Concern for productivity and efficiency' is not a central concern of human relations: rather, this could apply to the scientific management school.

'Awareness of the many different variables that influence and constrain a manager's behaviour' is a contribution of the contingency school.

'Proof of a clear link between job satisfaction, worker motivation and business success' has not yet been provided by any school of management or motivation theory: apart from anything else, business success depends on factors other than the productivity of the workers.