Which of the Following Is the Clearest Evidence of Employment

Which of the following is the clearest evidence of employment discrimination against minority employees?

A) the average wage of minority workers is lower than the average wage of whites.
B) the average hours worked by minority employees exceeds the hours worked by whites.
C) the mean number of years of schooling of minority workers is lower than that of whites.
D) the average wages of minority employees are lower than the average wages of whites with similar productivity characteristics.