The nurse is caring for an older adult client who is experiencing delirium. Which of the following should be the priority action by the nurse?

The correct answer is B: Obtain a medical history. This is the priority action because delirium in older adults can have various underlying causes such as infections, medication side effects, or metabolic imbalances. Obtaining a thorough medical history will help the nurse identify potential triggers for the delirium and guide appropriate interventions. Administering diazepam (A) can worsen delirium and should be avoided. Starting intravenous fluids (C) may be necessary but is not the priority until the underlying cause is identified. Raising 3 of the 4 side rails of the bed (D) is a safety measure to prevent falls but does not address the root cause of delirium.