How did the knights of labor participate in the struggle of american workers

The Knights of Labor attracted large numbers of workers hoping to improve their immediate conditions. As the Knights carried on strikes and organized along industrial lines, the threatened national trade unions demanded that the group confine itself to its professed labor reform purposes; when it refused, they joined in December 1886 to form the American Federation of Labor (AFL). The new federation marked a break with the past, for it denied to labor reform any further role in the struggles of American workers. 

C. it's a true fact. i know because we are studying about the great depression. so it best illustrates a claim of fact. thx. have a wonderful day!