A nurse plans to measure a client's temperature orally. Which action should the nurse take first to ensure an accurate measurement?

Rationale: A. Asking the client to breathe through their mouth during measurement is not necessary for accuracy and may actually cool the oral cavity, affecting the reading. This action is not the first step in ensuring a precise temperature measurement. B. Placing the thermometer under the tongue immediately is premature. If the client recently consumed hot or cold foods, beverages, or smoked, the oral temperature reading may be inaccurate. Verifying recent intake is essential before placement. C. Asking the client if they have consumed hot or cold food, beverages, or smoked within the last 15 minutes is the first and most important step to ensure accuracy. Recent oral intake or smoking can transiently elevate or lower oral temperature readings, leading to false results. Waiting at least 15 minutes after these activities helps ensure the measurement reflects the body’s core temperature. D. Instructing the client to keep their mouth slightly open may interfere with proper placement of the thermometer under the tongue. For accuracy, the client should close their lips gently around the probe, preventing external air from affecting the reading.