Question: What is the purpose of the NEF sending an Nsmf_EventExposure_Subscribe request to the SMF in step 4 of the Member UE Selection Assistance procedure?
Option 1: To request QoS monitoring for certain flows.
Option 2: To retrieve the list of target UEs that fulfill the QoS filtering criteria.
Option 3: To verify the authorization of the AF request.
Option 4: To discover the SMFs deployed in the Area of Interest.
Explanation: The NEF sends an Nsmf_EventExposure_Subscribe request to the SMF to request QoS monitoring for certain flows, which is necessary to detect the list of UEs that fulfill the QoS filtering criteria in real-time. This step allows the SMF to send an N4 Session Modification request to UPF for requesting QoS monitoring, enabling the NEF to receive Event Exposure notifications from the UPFs and derive the list of candidate UEs that fulfill the QoS filtering criteria.