Suitability of the software to fulfill the needs of the user exemplifies a quality attribute of what type of requirement?

The concept of suitability of software to fulfill user needs is fundamentally tied to the requirements that describe what the software must achieve in order to be considered effective for its intended purpose. This characteristic directly relates to functional requirements, which delineate specific behaviors, functions, or features that the software should provide.

Functional requirements are essentially the "what" of the software; they enable users to carry out specific tasks or achieve certain outcomes. In this context, if the software meets the users' needs adequately, it indicates that its functional requirements are well-defined and appropriately implemented.

While non-functional requirements describe how a system performs a function, focusing on aspects such as performance, usability, reliability, and other quality attributes, they do not directly address whether the software fulfills a user's specific needs or functionalities. Quality of Service and performance metrics are often examples of non-functional requirements that play a role in the overall user experience but are not the primary focus when assessing the suitability of a software solution concerning user needs. Therefore, the notion of software suitability is inherently linked to functional requirements, as these requirements define the system's specific capabilities and contributions to user goals.