One Reason That Wage Discrimination Based on Gender or Ethnicity

One reason that wage discrimination based on gender or ethnicity can continue is:

A) market interference or market failure associated with above-equilibrium wages.
B) market competition making it profitable to engage in discrimination.
C) it is justified by the marginal productivity theory of income distribution.
D) because,as the South African experience with apartheid showed,discrimination leads to more rapid economic growth.