Question: When should the UE include the CIoT user data container IE in a message?
Option 1: When the Payload container type IE is set to "CIoT control plane container"
Option 2: When the Payload container type IE is set to "CIoT user data container"
Option 3: When the UE is establishing a new PDU session
Option 4: When the UE is releasing an existing PDU session
Explanation: The correct answer is Option 2 because, according to the specification, the UE shall include this IE (CIoT user data container) when the Payload container type IE is set to "CIoT user data container". This indicates that the CIoT user data container IE is specifically used for carrying CIoT user plane data.