Question: What triggers the L2 U2U (Layer 2 User Equipment to User Equipment) Relay UE to release its configuration for a specific SL-DestinationIdentity, according to 3GPP RRC protocol specifications?
Option 1: Reception of the `sl-U2U-RelayUE-ToReleaseList` message containing the SL-DestinationIdentity value.
Option 2: Expiration of a timer set during the initial L2 U2U Relay UE configuration.
Option 3: Change in the network topology affecting the relay link.
Option 4: Handover of the UE to a different cell not supporting L2 U2U relay.
Explanation: The correct answer is Option 1 because, as per the specified behavior for an L2 U2U Relay UE, the release of its configuration for a specific SL-DestinationIdentity is directly triggered by receiving the `sl-U2U-RelayUE-ToReleaseList` message that includes this identity. This message is explicitly designed for this purpose within the RRC protocol, ensuring efficient management of relay resources in 5G networks (NR).