Question: How does the Network Exposure Function (NEF) determine whether to use the Non-IP Data Delivery (NIDD) API for a PDU session?
Option 1: Based on the presence of a 'NEF Identity for NIDD' in the subscription corresponding with the DNN and S-NSSAI information.
Option 2: Based on the UE's request for an Unstructured PDU session to the NEF during the PDU Session Establishment procedure.
Option 3: Based on the SMF's selection of the NEF for the PDU session.
Option 4: Based on the AF Identifier and UE Identity provided by the UE.
Explanation: According to the text, the NEF determines whether to use the NIDD API based on the presence of a 'NEF Identity for NIDD' in the subscription corresponding with the DNN and S-NSSAI information. This is specified in the paragraph as 'If the subscription includes a 'NEF Identity for NIDD' corresponding with the DNN and S-NSSAI information, then the SMF selects that NEF and uses the NIDD API for that PDU session.'