Statistical process control charts:

A$.$ indicate to the process operator the average outgoing quality of each lot.

B$.$ display upper and lower limits for process variables or attributes and signal when a process is no longer in control.

C$.$ are a graphic way of classifying problems by their level of importance, often referred to as the $80-20$ rule.

D$.$ indicate to the operator the true quality of material leaving the process.

E$.$ display the measurements on every item being produced.