In the 1930’s and 1940’s, African American industrial workers in the southern United States, who constituted 80 percent of the unskilled factory labor force there, strongly supported unionization. While the American Federation of Labor (AFL) either excluded African Americans or maintained racially segregated unions, the Congress of Industrial Organizations (CIO) organized integrated unions nationwide on the basis of a stated policy of equal rights for all, and African American unionists provided the CIO’s backbone. Yet it can be argued that through contracts negotiated and enforced by White union members, unions—CIO unions not excluded—were often instrumental in maintaining the occupational segregation and other forms of racial discrimination that kept African Americans socially and economically oppressed during this period. However, recognizing employers’ power over workers as a central factor in African Americans’ economic marginal ization, African American workers saw the need to join with White workers in seeking change despite White unionists’ toleration of or support for racial discrimination. The persistent efforts of African American unionists eventually paid off: many became highly effective organizers, gaining the respect of even racist White unionists by winning victories for White as well as African American workers. African American unionists thus succeeded in strengthening the unions while using them as instruments of African Americans’ economic empowerment. GWD-9-Q23 G-9-Q23: The author of the passage suggests which of the following about African American workers who participated in union activities in the 1930’s and 1940’s? A.
They believed that the elimination of discrimination within unions was a necessary first step toward the achievement of economic advancement for African Americans.
B.
They belonged exclusively to CIO unions because they were excluded from AFL unions. C.
They believed that the economic advancement of African American workers depended on organized efforts to empower all workers. D.
Some of them advocated the organization of separate African American unions because of discriminatory practices in the AFL and the CIO. E.
Many of them did not believe that White unionists in CIO unions would tolerate or support racial discrimination against African American workers.
我想问问B为什么不对呢？通篇没有提到AA可以加入AFL unions啊 | 
