Question: When is the "Uplink Data Status" Information Element (IE) included in a message by the User Equipment (UE)?
Option 1: When the UE has successfully transmitted all uplink user data.
Option 2: When the UE has no pending downlink user data to receive.
Option 3: When the UE is in idle mode and not transmitting any data.
Option 4: When the UE has uplink user data pending to be sent.
Explanation: The "Uplink Data Status" IE is included by the UE when it indicates that there is pending uplink user data to be sent, which helps in managing and coordinating the transmission of this data efficiently within the network.