Answer:
a. whether or not a process is out of control
Explanation:
A control chart is a graphical representation of fluctuations in a process, with time. The chart has a centre line, denoting mid average value.
The chart has upper & lower lines also, which depict the control limit. The upper & lower lines refer to upper & lower control limits respectively. They assist in analysing whether the process is going out of control range, surpassing the control range.
