Question: In the context of NF service framework for 5G Charging Function (CHF), what is the purpose of the `Nnrf_NFManagement_NFRegister` service invoked by CHF during registration?
Option 1: To register UE's IP address with the NRF for direct data transfer.
Option 2: To register CHF instance(s) and CHF service(s) instance(s), potentially including parameters like SUPI ranges, GPSI ranges, PLMN ranges, CHF Group ID, CHF set ID, and CHF service set ID.
Option 3: To update the billing cycle for a specific subscriber in real-time.
Option 4: To deregister all NF services from the NRF for maintenance purposes.
Explanation: The correct answer is Option 2 because, according to the NF service framework for 5G Charging Function, the `Nnrf_NFManagement_NFRegister` service is specifically used for registering CHF instances and their associated services with the NRF. This registration process may include a range of identifiers (SUPIs, GPSIs, PLMNs) and IDs (CHF Group ID, CHF set ID, CHF service set ID), which are crucial for service discovery and management within the 5G system's Service Based Architecture (SBA).