Final answer:
A thermometer calibrated using the ice-point method should be set to the freezing point of water on the Fahrenheit scale, which is 32°F.
Step-by-step explanation:
A thermometer calibrated by the ice-point method should be precisely set to the temperature where water freezes, which is a critical reference point in temperature measurement. According to the Fahrenheit scale, the freezing point of water is 32°F, whereas on the Celsius scale, it is 0°C. The calibration process involving the ice-point method ensures that the thermometer is accurate at this specific temperature.
Therefore, the answer to the student's question is: A thermometer calibrated by the ice-point method should be set to 32°F (option a). This ensures that it correctly reflects the point at which water turns to ice, which is essential for accurate temperature readings.