单项选择题

What  is the  key contribution of the  human  relations approach to  management

A.Proof of a  clear link  between job satisfaction, worker motivation  and  business success
B.Concern for productivity and  efficiency
C.Awareness of the  many different variables that influence and  constrain  a  manager's behaviour
D.Awareness of the  importance of group dynamics and  worker attitudes as an  influence on productivity