What Is the Definition of Rational Subgroups

Multiple Choice

What is the definition of rational subgroups?

A) They are those parts of a process that are identified as most likely to be special causes.
B) They are samples chosen to reflect only item-to-item variation in a process.
C) They are those samples in an s chart that are in control.
D) They are the specific groups of charts that we use to monitor a process.