Final answer:
The rifle in the cartoon likely alludes to the Sherman Antitrust Act, which was aimed at breaking up monopolies and trusts in order to maintain free competition. For U.S. western expansion, the Homestead Act played a crucial role by granting settlers land and promoting westward migration.
Step-by-step explanation:
The cartoon referenced in the student's question is likely criticizing either the ineffectiveness or the enforcement of federal laws intended to regulate commerce and prevent monopolies. Given the options provided, the law that would most clearly represent a rifle controlling or challenging monopolistic behavior would be the Sherman Antitrust Act. The Sherman Antitrust Act was the first federal act that outlawed monopolistic business practices. It was a significant step towards antitrust regulation by the American government, aiming to maintain free competition in the marketplace by preventing artificial price elevation through monopolies or trusts.
In terms of the actions taken by the U.S. government to fulfill the goal of western expansion, the Homestead Act would be the most relevant. This act encouraged western migration by providing settlers land at little or no cost, significantly aiding in the expansionist agenda of Manifest Destiny at the time.