Which statement accurately describes the relationship between functional and non-functional requirements?

The statement that all requirements can be categorized as either functional or non-functional accurately captures the essential distinction between these two types of requirements. Functional requirements specify what a system should do, detailing the behaviors, functions, and features that must be implemented. In contrast, non-functional requirements define the criteria that judge the operation of the system, such as performance, security, usability, and reliability.

This categorization is fundamental in systems engineering and software development, as it allows stakeholders to clearly understand what the system is expected to do (functional) and the quality attributes it must satisfy (non-functional). Understanding both categories aids in comprehensive requirement analysis and helps ensure a more complete understanding of user needs and system capabilities.

The other statements incorrectly represent the relationship between functional and non-functional requirements. Some suggest a ranking or diminish the importance of one type over the other, which is misleading, as both are essential for a well-rounded specification. Others may imply a simplistic relationship that does not reflect the complexity and significance each type of requirement has in the development process.