In a controlled laboratory environment, independent randomsamples of 10 adults and 10 children were tested by a psychologistto determine the room temperature that each person finds mostcomfortable. The study provided the following results:
  Adults    Children
Sample size   10 10
Sample mean (in degrees)  77.5             74.5
Sample variance 4.5   2.5
Which one of the following is the correct 99% confidenceinterval for the true difference in population mean temperaturesthat adults and children find most comfortable?