What is the main concern$/$purpose of Statistical Process Control $($SPC$)$ and Statistical Quality Control $($SQC$)?$ Select two $(2)$ statements that apply.

It keeps track of a process in order to reduce variation of improve quality.

It is used to document recommendations from customers and to record the improvements where needed.

It is concerned with checking data on reports for corporate personnel.

It is the application of statistical techniques to the output $($quality$)$ of a process.