The correct answer is that a potential new factory employee would refuse to sign a yellow-dog contract because promising not to join a union would strip the employee of his ability to protest workplace injustices with the support of an organized workers’ group.
A yellow dog contract was an employment contract that included a commitment by the worker not to join a union. These contracts were widely extended in the United States until the 1930s to prevent the formation of trade unions, and they frequently gave them the power to take action against trade union delegates. In 1932, yellow dog contracts were abolished in the United States by the Norris-LaGuardia Act.