Which data set has the smallest standard deviation?

A. 55, 90, 34, 78, 15, 20, 19
B. 1000, 1001, 1002, 1000, 1001, 1001
C. 1, 9, 120, 9, 1, 1, 9
D. 7, 8, 89, 1005, 23400, 5, 3