Question: What is the condition under which the UE and PDN GW exchange protocol configuration options via the Extended protocol configuration options IE, instead of the Protocol configuration options IE?
Option 1: When the UE is in WB-S1 mode and the APN requested for the PDN connection is for non-UAS services.
Option 2: When the network has indicated support of the Extended protocol configuration options IE in the last ATTACH ACCEPT or TRACKING AREA UPDATING ACCEPT message, but only if the UE is in NB-S1 mode.
Option 3: When the PDN Type requested for the PDN connection is IP or Ethernet, and the UE has indicated support of the Extended protocol configuration options IE in the last ATTACH REQUEST or TRACKING AREA UPDATING REQUEST message.
Option 4: When all of the following conditions are met: the UE is in NB-S1 mode; the APN requested for the PDN connection is for UAS services; the PDN Type requested for the PDN connection is non-IP or Ethernet; and the network has indicated support of the Extended protocol configuration options IE in the last ATTACH ACCEPT or TRACKING AREA UPDATING ACCEPT message.
Explanation: According to the text, the UE and PDN GW exchange protocol configuration options via the Extended protocol configuration options IE when all the specified conditions are met. These conditions include the UE being in NB-S1 mode, the APN requested for the PDN connection being for UAS services, the PDN Type requested for the PDN connection being non-IP or Ethernet, and the network having indicated support of the Extended protocol configuration options IE in the last ATTACH ACCEPT or TRACKING AREA UPDATING ACCEPT message.