Concept:The daily temperature range is the difference between the highest and lowest temperatures recorded in one day.Explanation:A combined maximum and minimum thermometer records both the hottest and coldest temperatures of the day.The hottest reading is the maximum daily temperature.The coldest reading is the minimum daily temperature.The difference between them is calculated as:Diurnal range of temperature=Tmax−TminThis difference represents how much the temperature varied during that single day.Answer:A. Diurnal range of temperature