【单选题】

"Their" method cannot be adapted to deal with the more general case because they have not realized that ______.
A．a fall in the value of real wages would lead to a withdrawal of the labor from market of labor

B．a reduction in the existing level of money-wages would lead to a withdrawal from the labor market of labor
C．the supply of labor is not a function of real wages
D．the demand of labor is only for a minimum money-wages