Final answer:
To keep a patient from consciously controlling their breathing during an assessment, the nurse should assess respiration before measuring the blood pressure.
Step-by-step explanation:
To keep a patient from consciously controlling their breathing during an assessment, the nurse should assess respiration before measuring the blood pressure. By assessing respiration before other activities, the nurse can prevent the patient from consciously altering their breathing pattern. This way, the respiratory rate can be accurately measured and provide valuable information about the patient's condition.