Statistical quality control is the use of statistical techniques to:

A) improve profit margins.
B) determine appropriate debt levels.
C) help make good investment decisions.
D) All of the options listed
E) None of the options listed

Statistical quality control primarily focuses on monitoring and controlling processes to ensure that the quality of products and services meets a certain standard. It does not directly involve improving profit margins, determining appropriate debt levels, or making investment decisions, although indirectly, quality control can impact these areas by ensuring product quality and customer satisfaction.