Question: In an L2 (Layer 2) U2N (User-to-Network) Relay UE scenario, what action is taken by the UE when it receives a `sl-RemoteUE-ToReleaseList` triggering a release, for each SL-DestinationIdentity value included in the list, if a PC5 RRC connection exists?
Option 1: Modify the configuration associated with the L2 U2N Remote UE.
Option 2: Establish a new PC5 unicast link to maintain connectivity.
Option 3: Ignore the release trigger for existing connections.
Option 4: Indicate upper layers to trigger PC5 unicast link release.
Explanation: This is correct because, according to the specified behavior for an L2 U2N Relay UE receiving a `sl-RemoteUE-ToReleaseList`, if there's a current PC5 RRC connection to an L2 U2N Remote UE with the specified SL-DestinationIdentity, the UE must notify its upper layers to initiate the release of the PC5 unicast link. This ensures proper disconnection and resource management within the network.