A. It is the most widely used strategy for statistical quality assurance
B. The “Six Sigma” refers to six standard deviations
C. It is the most widely used strategy for statistical quality assurance AND The “Six Sigma” refers to six standard deviations
D. A Formal Technical Review(FTR) guideline for quality walkthrough or inspection

Explanation: The Six Sigma uses data and statistical analysis to measure and improve a company’s operational performance .