The correct answer is C) Sherman Anti-trust Act.
The Sherman Anti-trust Act was used against unions.
On July 2, 1890, the United States Congress enacted the Sherman Anti-trust Act to limit monopolistic business practices. It prohibited trusts. The US Congress had the power to regulate interstate trade and the Sherman Act prove it. It had the authority to dissolve trusts. In that time, the trusts dominated the US industry and had affected the healthy competition that benefited the market.