Here are three given sets: Set A: {8, 9, 10, 13} Set B: {10, 10, 10, 10} Set C: {0, 0, 20, 20} Which of the following statements must be true? I. The averages of the three sets are equal II. The standard deviations of all three sets are positive III. Set C has the greatest standard deviation.
A. I & III only
B. I & II only
C. II & III only
D. I, II, & III