What does "critical to quality" (CTQ) refer to?

"Critical to Quality" (CTQ) refers specifically to key measurable characteristics that are essential to meet customer requirements. These characteristics define the attributes of a product or service that customers consider vital for their satisfaction. In Six Sigma, identifying CTQs is crucial because it helps organizations focus on the elements that directly impact customer satisfaction and product quality. By measuring and controlling these specific characteristics, a company can work towards reducing defects, improving processes, and increasing overall quality to better meet customer needs.

The other options do not correctly capture the essence of CTQs. For instance, characteristics that are not measurable or irrelevant aspects of product quality do not provide any useful metrics for ensuring quality or meeting customer expectations. Similarly, considering all features of a product as CTQs would dilute the focus needed to prioritize and improve those aspects that truly matter to the customer. Hence, the emphasis on key measurable characteristics makes option B the best choice for understanding what CTQs represent in the context of quality management and Six Sigma practices.