The quality control office tests bottles of shampoo to see if the filling machines are putting the proper amount in each bottle. They do not want to shut down production unless there is strong evidence indicating that the machines are not functioning properly. After testing a sample of bottles, the quality control manager decides to leave the filling machines operating. Actually, however, the filling machines are not operating properly. This is an example of:

A. a Type I error.
B. a Type II error.
C. a correct decision.