Final answer:
The correct instruction before a Romberg test is for the patient to keep their eyes closed to evaluate balance without visual cues.
Step-by-step explanation:
Before performing the Romberg test, the correct statement a nurse should make to a client is: "Keep your eyes closed throughout the entire test." This is an essential step because the point of the Romberg test is to assess balance and proprioception without the aid of visual cues. The patient needs to rely on proprioceptive and vestibular inputs to maintain balance, which the test is designed to evaluate. If they experience swaying or falling, it may indicate a deficit in proprioceptive function or issues within the vestibular or cerebellar systems.