Which of the Following Statements Is TRUE

Multiple Choice

Which of the following statements is TRUE?

A) If a process is in statistical control, assignable causes of variation should be sought.
B) If a process is in statistical control, there are no causes of variation.
C) If a process is out of statistical control, there are only assignable causes of variation.
D) When assignable causes of variation exist, the process generates different distributions of the quality characteristic over time.