What statement describes the application layer as defined in the software-defined networking architecture?

Handling packets based on rules provided by the controller is the role of the infrastructure (data) layer, which contains the physical and virtual network devices that perform actual packet forwarding.

Collecting network status such as topology and usage statistics is a function of the control layer, which gathers information from devices via southbound APIs to maintain a global network view.

The SDN application layer contains business and network applications - such as traffic engineering, security, and management tools - that express high-level network intent to SDN controllers through northbound APIs, allowing controllers to translate that intent into concrete forwarding rules pushed down to the data plane.

Processing instructions and requirements sent by networking components describes the control layer's function of translating application-layer intent into device-level forwarding decisions.