When refilling a prescription that requires a child-resistant container, the pharmacist must always replace which of the following?

When a prescription is refilled that requires a child-resistant container, it is essential for the pharmacist to ensure safety by providing a new plastic container each time. Child-resistant containers are specifically designed to add an extra level of safety for medications, especially to prevent accidental ingestion by children.

Using a new container safeguards the integrity of the medication and ensures that it is properly sealed to maintain efficacy and reduce the risk of contamination. Additionally, the child-resistant feature of these containers can degrade over time or through repeated use, so fresh containers ensure ongoing compliance with safety regulations.

Other aspects like the medication itself, the paper prescription, or the medication label may not necessarily need to be replaced in every refill, as they do not directly relate to the safety mechanism intended for child protection. Hence, changing the plastic container is the key action in this context.