Statistical process control charts: Select one: aindicate to the operator the true quality of material leaving the process. b$.$ display upper and lower limits for process variables or attributes and signal when a process is no longer in control. c$.$ indicate to the process operator the average outgoing quality of each lot. $.$ display the measurements on every item being produced e$.$ are a graphic way of classifying problems by their level of importance, often referred to as the $80-20$ rule.