Which legislation established a minimum wage and limited the hours of work per week in the United States?

The Fair Labor Standards Act is the correct answer as it was enacted in 1938 and established several key labor standards in the United States. This significant piece of legislation mandated a federal minimum wage, initially set at 25 cents per hour, and established regulations to limit the workweek to 44 hours, later adjusting to 40 hours. Its purpose was to protect workers from unfair labor practices and to promote fair pay and decent working conditions, reflecting the labor reforms and concerns of the time, especially in the wake of the Great Depression.

The other options pertain to different aspects of labor rights and social welfare. The Wagner Act primarily focused on workers' rights to unionize and collectively bargain. The Social Security Act established a social safety net providing financial assistance to the elderly and unemployed. The National Labor Relations Act further protected the rights of workers in terms of union organization and labor practices but did not address wage minimums or work hour limits.