Question: How should the UE handle unknown IEs in a message that are not encoded as "comprehension required"?
Option 1: The UE shall process them as if they were mandatory.
Option 2: The UE shall ignore them and continue processing the rest of the message.
Option 3: The UE shall send an error message to the network indicating that it cannot understand the IEs.
Option 4: The UE shall terminate the connection with the network.
Explanation: According to the NAS protocol, if an IE is unknown and not encoded as "comprehension required", the UE should ignore it and continue processing the rest of the message. This ensures that the UE can still understand and process the rest of the message even if it encounters unknown IEs.