The answer is The Wagner Act.
The Wagner Act, officially known as the National Labor Relations Act of 1935, is the law that guaranteed most workers the right to organize into labor unions. It established the National Labor Relations Board (NLRB) to oversee and enforce labor laws, and it protected the rights of employees to engage in collective bargaining and to take collective action, including strikes.
The Glass-Steagall Act, enacted in 1933, primarily focused on banking reforms and the separation of commercial and investment banking. It did not address labor rights or the organization of labor unions.
The Social Security Act, passed in 1935, was designed to provide financial assistance to the elderly, the unemployed, and the disabled. It did not pertain to labor unions or workers' rights to organize.
The Securities Exchange Act of 1934 was aimed at regulating the securities industry and stock exchanges. It established the Securities and Exchange Commission (SEC) but did not involve labor rights or union organization.