Which category do all the following drugs belong to, except one?

The category "Grand-fathered Drugs" is the correct answer because it refers to a specific group of drugs that were approved under older regulatory standards and are not typically classified under the same criteria as more recent drug approvals. This concept does not apply broadly to the other categories, which encompass more general classifications of medications based on their usage, accessibility, and regulatory status.

Prescription Medications are those that require a doctor's authorization, while Controlled Substances are drugs that are regulated due to their potential for abuse and dependence. Over-the-Counter Drugs are medications that can be purchased without a prescription because they are considered safe for public use without professional supervision. Each of these categories serves a specific purpose in pharmacology and drug regulation, unlike the more nuanced and less commonly referenced category of Grand-fathered Drugs. Hence, this distinction clarifies why Grand-fathered Drugs stand apart from the other categories mentioned.