Which law requires pharmaceutical manufacturers to prove a drug's purity, strength, and safety before it can be sold?

The Food, Drug, and Cosmetic Act of 1938 is the legislation that mandates pharmaceutical manufacturers to demonstrate a drug's purity, strength, and safety before it can be marketed and sold to the public. This law was enacted in response to earlier scandals involving unsafe and ineffective medications, leading to a framework that requires rigorous testing and approval processes.

Under this law, the Food and Drug Administration (FDA) is granted the authority to oversee the safety and efficacy of drugs, ensuring that any new medications meet specific standards before they are available for consumer use. This act is fundamental in protecting public health by ensuring that only safe and effective drugs are accessible to patients.

The other options refer to different aspects of healthcare and drug regulation but do not cover the requirement that manufacturers prove their products' suitability for sale in the same way. The Comprehensive Drug Abuse Prevention and Control Act focuses primarily on the regulation of controlled substances. The Drug Enforcement Administration Act pertains to the enforcement of drug law compliance but is not the law that requires demonstrable proof of drug quality before market entry. The Medicare Modernization Act addresses health insurance and drug coverage rather than the approval of drug safety and efficacy.