Final answer:
The US Food and Drug Administration (FDA) is responsible for rigorous testing of medications before making them available to the public.
Step-by-step explanation:
The regulatory agency responsible for rigorous testing of medications before making them available to the public in the United States is the US Food and Drug Administration (FDA).
The FDA is responsible for regulating and supervising various aspects of public health, including food safety, pharmaceutical drugs, medical devices, and cosmetics. It ensures the safety and efficacy of medications by setting standards, conducting testing, and reviewing the data provided by pharmaceutical companies.
For example, the FDA regulates almost every facet of prescription drugs, including testing, manufacturing, labeling, advertising, marketing, efficacy, and safety.