Two students in an economics class, Harry and Sally, are discussing the problems with gender discrimination in the labor market. They both agree that men and women should be treated equally. Sally claims that the significant differences in the ratio of men to women in the market for construction workers, a relatively higher-paying field, compared to grocery clerks, a relatively lower-paying field, is abhorrent and a result of discrimination. Harry responds using the analysis he learned in the lecture on labor supply.