Final answer:
When a nurse receives a telephone call from a parent requesting the status of a client, they should confirm the caller's identity using a pre-established code.
Step-by-step explanation:
When a nurse working on a medical-surgical unit receives a telephone call requesting the status of a client from an individual who identifies themselves as the client's parent, the nurse should confirm the caller's identity using a pre-established code as the appropriate action to take. It is important to protect patient privacy and ensure that information is only disclosed to authorized individuals.