For a group experiment, your science class measured the fine-particulate concentrations in the air at random places around campus and estimated a sample average of 12 μg/m³ (micrograms per cubic meter). If 196 readings were taken, and the standard deviation of the sample measurements was 3.5 μg/m³, you are 99.7% confident that actual concentration of fine particulates at school is A.) 1.5 μg/m³- 22.5 μg/m³
B.) 5 μg/m³- 19 μg/m³
C.) 11.5 μg/m³- 12.5 μg/m³
D.) 11.25 μg/m³ - 12.75 μg/m³