The correct answer is A Samuel Gompers's American Federation of Labor - The American Federation of Labor was founded in 1886 by Samuel Gompers. It was formed by several unions of skilled white workers. It mainly focused on improving wages, shorter hours and better working conditions for workers.
Letter B is incorrect because The American Railway Union was focused only on railway workers and it wasn’t an organization of craft unions.
Letter C is incorrect because it was a union that combined general unionism and industrial unionism, organizing its members by their industry of employment.
Letter D is incorrect because it started as a secret organization that meant to protect workers from employers retaliations
