Final answer:
Using the Sherman Antitrust Act of 1890, Roosevelt went on the attack against monopolies, increasing his popularity among those who favored regulation of big business.
Step-by-step explanation:
Using the Sherman Antitrust Act of 1890, Roosevelt went on the attack against monopolies. The Sherman Antitrust Act was enacted to promote fair competition and prevent monopolies from forming. Roosevelt saw monopolies as a threat to the free market and used the act to break up several trusts, including the Northern Securities Company and Standard Oil. This action increased his popularity among those who favored regulation of big business.
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