Which of the data sets shown below has a mean that is less than 28? Select all that apply.
A) 24, 31, 25, 29, 26, 21
B) 18, 33, 32, 16, 34, 29
C) 32, 31, 25, 28, 31, 27
D) 12, 41, 44, 13, 20