Lowest standard deviation of measurements
As the Quality Control Manager of a chemical company, you are asked to decide between several process methods that are supposed to uniformly mix 37.4 milligrams into a chemical solution. The resulting solutions from each process are sample tested for uniformity. The test samples yielded the following results of percentage powder mixed in the solution:

Method A: 0.13%, 0.21%, 0.009%, 0.014%
Method B: 0.10%, 0.006%, 0.015%, 0.11%, 0.16%
Method C: 0.006%, 0.09%, 0.07%
Method D: 0.18%, 0.16%, 0.19%, 0.17%

Which method would be the best choice to provide a uniform mixture??? (Hint: The best selection would be that resulting in the lowest standard deviation of measurements
Method A
Method B
Method C
Method D