What Is a Concern About the Single Rule That Dictates

What is a concern about the single rule that dictates that control values must fall within two standard deviations of the mean?

A) It can only be trusted when greater than ten different controls have been tested.
B) It can trigger false alarms that cause rejection of acceptable runs.
C) It is insufficient to detect errors created by compromised controls.
D) It is only applicable to instruments previously calibrated by the International Standards Committee.