Which of the following is required on a valid prescription regarding the prescriber?

A valid prescription must include specific information about the prescriber to ensure that the medication is being prescribed legally and appropriately. The prescriber's DEA (Drug Enforcement Administration) number is particularly important when controlled substances are involved, as it indicates that the prescriber is authorized to prescribe these types of medications. This number is essential for pharmacies to verify the legitimacy of the prescription and to maintain compliance with federal regulations regarding the prescription and dispensing of controlled substances.

Other options such as the prescriber's favorite medication, hobbies, or professional experience do not pertain to the legal and clinical requirements of a prescription. They do not provide necessary information that assures the pharmacy or healthcare provider of the prescriber's authority or competence in prescribing medications. Therefore, including the DEA number is both a legal necessity and a crucial element of the prescription process.