This is a standard deviation contest. Which of the following sets of four numbers has the smallest possible standard deviation?
A7, 8, 9, 10
B5, 5, 5, 5
C0, 0, 10, 10
D0, 1, 2, 3
A7, 8, 9, 10
B5, 5, 5, 5
C0, 0, 10, 10
D0, 1, 2, 3