Which of the Following Provides the Clearest Evidence of Employment

Which of the following provides the clearest evidence of employment discrimination by firms against minority employees?

A) Hours worked by minority employees are greater than hours worked by whites.
B) The mean amount of schooling of minorities is less than that of whites.
C) The average wage of minority workers is less than the average wage of whites with similar productive characteristics.
D) The average wage of minority workers is less than the average wage of whites.