Final answer:
Craft unions, led by Samuel Gompers, focused on skilled workers and fought for improved wages and working conditions.
Step-by-step explanation:
Samuel Gompers led craft unions like the American Federation of Labor (AFL). Craft unions, unlike industrial unions, focused on skilled laborers, so option b) Focused on skilled workers is correct. Craft unions did not include all trades or allow unskilled labor, so options a) Inclusive of all trades and c) Allowed unskilled labor are incorrect. Craft unions like the AFL primarily supported the interests of the workers and fought for improved wages and working conditions, so option d) Supported industrialists is also incorrect.