Final answer:
The nurse should assess the client with a new onset of confusion and restlessness first, as it could indicate a life-threatening condition such as sepsis or a brain injury.
Step-by-step explanation:
Regarding the group of clients a nurse should assess, priorities are typically set based on acuity and potential for rapid deterioration. In this scenario, the nurse should assess the client with a new onset of confusion and restlessness first. This symptom could indicate a serious and life-threatening condition like sepsis or a brain injury, and such changes in mental status are often considered red flags in clinical practice. A client with a history of hypertension complaining of a headache could be experiencing a hypertensive crisis, which also needs to be addressed promptly. However, the potential for immediate life-threatening consequences is usually lower than that of acute mental status changes. A client who had abdominal surgery and reports incisional pain is likely experiencing expected postoperative pain, while a client receiving chemotherapy with complaints of nausea is experiencing a common side effect of the treatment.