Question: What is the purpose of the Nsmf_EventExposure_Subscribe service operation in the 5G System (5GS)?
Option 1: To unsubscribe from event notifications on a specified PDU Session.
Option 2: To subscribe or modify a subscription for event notifications on a specified PDU Session or for all PDU Sessions of one UE, group of UE(s) or any UE.
Option 3: To request the first corresponding event report for a subscription.
Option 4: To determine the UPF to contact for a subscription related to UPF event exposure.
Explanation: The Nsmf_EventExposure_Subscribe service operation is used by an NF to subscribe or modify a subscription for event notifications on a specified PDU Session or for all PDU Sessions of one UE, group of UE(s) or any UE. This allows the NF to receive event notifications from the SMF or UPF, enabling it to take appropriate actions based on the events reported.