Pick the best definition of quality:

The definition of quality that aligns best with established testing and quality assurance principles is conformance to requirements. This definition emphasizes that quality is achieved when a product meets the specified requirements and standards set forth during its development. It highlights the importance of understanding and documenting what is expected from the product, ensuring that all functional and non-functional requirements are fulfilled.

By focusing on conformance to requirements, organizations can assess whether a product is fit for its intended use and meets the needs of its stakeholders. This perspective is widely acknowledged in various quality frameworks, including ISO standards, where adherence to requirements is a foundational element in determining quality.

Other definitions like "zero defects" or "work as designed" might suggest a quality perspective but do not encompass the broader scope that conformance to requirements does. For example, zero defects implies perfection, which is unrealistic in many contexts. Similarly, "work as designed" suggests that if the product operates as intended, it is of high quality, but it doesn’t account for whether those intended functions are what the users truly need or expect. Therefore, conformance to requirements provides a more comprehensive and applicable understanding of quality in the context of software testing and overall product development.