Final answer:
The Poison Prevention Packaging Act mandates that most over-the-counter and prescription medications use child-resistant containers to prevent accidental poisoning in children.
Step-by-step explanation:
The law that requires most over-the-counter medications and prescription medications to use child-resistant containers is the Poison Prevention Packaging Act (PPPA). The PPPA was enacted to protect children from accidental poisoning by household substances, including medications. It mandates that a wide range of household substances must be packaged in child-resistant packaging to prevent young children from opening them easily.