Final answer:
The common purpose of the legislative acts mentioned was to promote the general welfare of the American public, by establishing infrastructures, ensuring consumer safety, and preserving natural resources, alongside economic development and consumer protection. The correct option is (4) promote the general welfare of the American public
Step-by-step explanation:
The common purpose of the legislative acts such as the Federal Highway Act of 1921, the Meat Inspection Act, the Pure Food and Drug Act, and the National Park Service creation was to promote the general welfare of the American public.
By creating infrastructures like highways, regulating businesses, ensuring consumer safety, and preserving natural resources, these acts were aimed at improving the economic and social prosperity of the nation.
Similarly, the establishment of the Federal Reserve was to stabilize the banking system, which is aligned with the general welfare of society.
Additionally, acts like the Homestead Act and the support for the transcontinental railroad were meant to further economic development and support the nation's expansion, which again ties back to promoting the general welfare.
The Republican policies of the 1920s, although primarily designed to favor business interests, also had the consequence of benefiting the middle class through various tax reductions and spending cuts.
Likewise, the laws enacted during the Johnson administration were focused on enhancing consumer protections, improving transportation and the environment, and supporting cultural initiatives, thereby contributing to the overall welfare of the American public. The correct option is (4) promote the general welfare of the American public