A requirement stating how the system should react to particular inputs is a _____ requirement.

### Why this is right Functional requirements describe services and explain how a system should react to particular inputs. They define what the system does. ### The concept A functional requirement describes behavior that users or other systems can observe. It differs from a non-functional requirement, which describes qualities or constraints such as reliability, response time, or storage needs. Functional requirements can be misunderstood if the user's intention and the developer's interpretation differ. ### Terms - **Input**: Data or a signal supplied to a system. ### Remember If a requirement describes a response or service, it is functional.