A condominium complex contains 20 units. The following data shows the number of individuals living in each unit.
2 2 3 1 4 3 5 2 1 3
4 4 2 2 3 5 1 2 3 5
Using the first row of data as a sample, the sampling error is ________.
A) 0.00
B) 0.40
C) -0.90
D) 0.25