Question: When should the NAS message container Information Element (IE) be included in a REGISTRATION REQUEST message sent by the User Equipment (UE)?
Option 1: If the UE has an invalid 5G NAS security context.
Option 2: If the UE is sending a REGISTRATION REQUEST message as an initial NAS message and needs to send cleartext IEs.
Option 3: If the UE is sending a REGISTRATION REQUEST message as an initial NAS message, has a valid 5G NAS security context, and needs to send non-cleartext IEs.
Option 4: If the UE does not have a valid 5G NAS security context but needs to send non-cleartext IEs.
Explanation: The correct answer is Option 3 because the NAS message container IE should be included in a REGISTRATION REQUEST message sent by the UE as an initial NAS message when it has a valid 5G NAS security context and needs to send non-cleartext IEs. This ensures that sensitive information can be securely transmitted between the UE and the network.