Question: What is the primary purpose of the Nnef_NIDD_GroupDeliveryNotify service operation in the 5G System (5GS)?
Option 1: To request Group MT NIDD operations from the AF.
Option 2: To inform the AF of the aggregated response of Group MT NIDD operations.
Option 3: To provide Re-transmission Time(s) to the NEF for Group MT NIDD operations.
Option 4: To invoke the Nnef_NIDD_Delivery operation with an External Group Identifier.
Explanation: The correct answer is Option 2 because the Nnef_NIDD_GroupDeliveryNotify service operation is specifically used by the NEF to inform the AF of the aggregated response of Group MT NIDD operations, as stated in the description. This highlights the role of this service operation in facilitating communication between the NEF and AF regarding group message delivery status.