Final answer:
Antitrust Legislation encourages competition and discourages monopolies by preventing anti-competitive practices.
Step-by-step explanation:
The act that encourages competition and discourages monopolies is Antitrust Legislation. Antitrust legislation refers to a collection of laws and regulations aimed at promoting competition and preventing the abuse of monopoly power. These laws are enforced by government agencies, such as the Federal Trade Commission (FTC) and the Department of Justice (DOJ), and they prevent companies from engaging in anti-competitive practices, such as price-fixing, monopolistic mergers, and unfair trade practices.