Let's start with Ashenfelter's study on line 47. The study concludes that craft unions increase the differential between wages earned by white employees and wages earned by black employees. In short, craft unions allow white people to make more money because black people are traditionally excluded from these unions (line 51). Answer choice A reflects this finding from Ashenfelter's study. Craft unions have been successful in ensuring that the wages of their members (white workers) remain higher than the wages of non-union (black) workers in the same occupational groups.
