What is commonly required for the prescription of a dangerous drug?

A written prescription is commonly required for the prescription of a dangerous drug because it serves as a formal and legal document that outlines the specific medication, dosage, and instructions for the patient. This requirement is in place to ensure patient safety and to maintain appropriate control over the distribution of drugs that may have a potential for abuse or harmful side effects. A written prescription allows pharmacists to verify the legitimacy of the medication being dispensed and helps keep accurate records for regulatory and safety purposes.

Other options such as oral agreements, any type of contract, or parole approval do not meet the legal standards established for prescribing dangerous drugs. Oral agreements lack the formal documentation necessary for legal accountability, and contracts can vary widely and do not specifically address the legal requirements of drug prescriptions. Parole approval does not relate to the prescription process at all, as it pertains to legal supervision rather than medical prescriptions.