Management Consultants Work in Pleasant Surroundings at Low Risk of Injury,but

Management consultants work in pleasant surroundings at low risk of injury,but they generally receive higher pay than sanitation workers who face a health risk by working in unpleasant conditions.Based on this information,which of the following must be true?

A) Management workers receive a higher pay because their wages include a compensating wage differential.
B) Since there is free mobility of labor,sanitation workers must have chosen not to move to a higher-paying job.
C) Wages of management consultants and sanitation workers are not comparable due to differences in the level of human capital investment.
D) Management consultants are paid a higher wage to compensate for the intrinsic attractiveness of their jobs.