What term describes the basis for agreement on what a software product is expected to do?

The correct choice is "Requirements specifications" because this term refers to a detailed description of the functionalities, features, and constraints of a software product. It establishes a common understanding among stakeholders about what the software should accomplish, serving as a formal agreement that guides the development process. Requirements specifications typically include user requirements, system requirements, and possibly functional and non-functional requirements, ensuring that both developers and clients have clear expectations.

In contrast, an implementation plan outlines how the project will be executed, detailing timelines, resources, and strategies but does not define the requirements of the software itself. Software architecture focuses on the high-level structure and design of the software system rather than the specifications of what it should do. Quality assurance pertains to the processes and techniques used to ensure that the software meets the established requirements; it is essential for verifying that the product aligns with the requirements after development but does not define what those requirements are.