Which of the following statements about employment discrimination is true? a. Employers who discriminate against blacks and women will have lower costs than rival firms that hire employees strictly on the basis of productivity. b. Employment discrimination occurs when some employees are treated differently from similarly productive employees because of a characteristic such as ethnicity or gender. OcEven though the actual earnings of Asian-American men are substantially less than those of white men, after adjustment for productivity differences, the earnings of the two groups are approximately equal O d. The empirical evidence indicates that the earnings gap between white men and black men is entirely the result of differences in productivity between the two groups.