Question: What is the primary purpose of the Nnef_ECSAddress_Subscribe service operation in the 5G System?
Option 1: To update the ECS Address Configuration Information for a specific UE.
Option 2: To retrieve the current ECS Address Configuration Information from the NEF.
Option 3: To allow NF consumers to subscribe to notifications of changes to ECS Address Configuration Information.
Option 4: To cancel an existing subscription to ECS Address Configuration Information.
Explanation: The Nnef_ECSAddress_Subscribe service operation is used by NF consumers to explicitly subscribe to notifications of changes to ECS Address Configuration Information, as indicated in the description. This allows NF consumers to receive updates when the configuration information changes, enabling them to take necessary actions.