Question

What law recognized the right of workers to join a labor union? A. The Keynes Act B. The Wagner Act C. The Smith Act D. The Fair Labor Standards Act

Answer 1

B. The Wagner Act

The "Wagner Act" (so-called after its Senate sponsor) was officially the National Labor Relations Act of 1935.  
The Wagner Act listed and prohibited five unfair labor practices, as follows: 

1. Interfering with the rights of employees, including freedom of association and the freedom to join labor organizations.2. Attempting to dominate or interfere with the formation or administration of any labor organization.3. Discriminating in hiring or tenure of employment because of membership in a labor union.4. Discriminating against employees who file charges or testify.5. Refusing to engage in collective bargaining with those serving as representatives of the labor force.