In the two-drawer method for filing prescriptions, what must CIII-CV drugs have?

In the two-drawer method for filing prescriptions, controlled substances classified as Schedule III to V (CIII-CV) must be identified with a red "C" in the corner of the prescription. This marking is essential as it allows for easy identification of controlled substances within the pharmacy's filing system, which helps ensure proper handling and records management as required by federal and state regulations.

The red "C" indicates that these medications are subject to more stringent regulations than non-controlled substances, thus promoting accountability and security in their storage and dispensing. It also facilitates quick reference for pharmacists and pharmacy staff, especially during inspections or audits, ensuring compliance with legal standards regarding controlled substances.

Other options, while they may refer to different filing preferences or practices, do not serve the purpose of identifying CIII-CV prescriptions according to the established regulations in pharmacy practice.