Which of the Following Statements About In-Control and Out-Of-Control Processes

Multiple Choice

Which of the following statements about in-control and out-of-control processes are true?
I. The mean chart and range chart always show that processes are in control.
II. A mean chart can be in control,while a range chart can be out of control.
III. A mean chart can be out of control,while a range chart can be in control.

A) I only
B) II only
C) II and III
D) I and III