What defines a "checklist" in Quality Assurance (QA)?

A checklist in Quality Assurance (QA) serves as a systematic tool designed to ensure that all necessary tests have been conducted thoroughly and consistently. It provides a structured way to track testing activities, making it easier to confirm that each aspect of the product or system has been examined against predefined criteria. This is crucial in QA because it helps maintain quality standards and reduces the risk of overlooking important tests, ultimately leading to more reliable deliverables.

In contrast, the other choices represent distinct types of documentation or tools that do not pertain directly to the function of a checklist in QA. A project timeline focuses on scheduling and deadlines, a summary of stakeholder requirements captures project expectations, and a statement of system design principles establishes the foundational guidelines for the architecture of the system. None of these documents provide the same level of functional support for ensuring the completeness and thoroughness of testing as a checklist does.