Question: When should a User Equipment (UE) include an RRC Transaction Identifier in an Uplink (UL) message, according to guidelines for Evolved Universal Terrestrial Radio Access (E-UTRA)?
Option 1: Always, in every UL message to ensure consistent tracking.
Option 2: Only when the UE is transitioning from RRC_CONNECTED to RRC_IDLE state.
Option 3: When the UL message is a direct response to a Downlink (DL) message without an RRC Transaction Identifier.
Option 4: When the UL message requires a direct Downlink (DL) response message from the network.
Explanation: This option ensures that the network can properly correlate the UE's request with its subsequent response, facilitating efficient communication in E-UTRA networks, as it pertains to messages requiring direct responses.