Final answer:
A sign indicating closure must be displayed when a prescription department is closed to inform the public and comply with health regulations.
Step-by-step explanation:
When a prescription department is closed, regulations often require that a sign be displayed indicating that it is not currently operational. This sign helps inform the public and ensure compliance with health and safety regulations. It's important for pharmacies to adhere to these guidelines to maintain proper pharmacy practice standards. The exact wording or type of sign can vary by jurisdiction, but generally, it must be clear and conspicuous to anyone seeking pharmacy services.