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.Therefore, the difference between them is:Diurnal range of temperature=Maximum temperature−Minimum temperatureThis difference is called the diurnal range of temperature because it covers one full day, or diurnal period.Answer:A. Diurnal range of temperature