Which of the Following Explains How a Violation of Westgard $\bar{x}+2 s$

Which of the following explains how a violation of Westgard Rule R₄s is identified?

A) The difference between two consecutive data points is at least 4 SD, and one data point lies
above $\bar{x}+2 s$ and the other lies below $\bar{x}-2 s$ .
B) The result from 2 single control run lies outside the range $\bar{x} \pm 3 s$
C) The result from one control lies above $\bar{x}+2 s$ , and the result from a different control lies
below $\bar{x}-3 s$ .
D) Both A and C are correct.