Question: What is the primary purpose of the ProSe Relay UE ID in Proximity-based services (ProSe)?
Option 1: To identify the serving cell for a UE
Option 2: To authenticate the UE with the network
Option 3: To identify the link layer address used for ProSe direct communication by a ProSe UE-to-network relay UE
Option 4: To prioritize traffic for emergency services
Explanation: The ProSe Relay UE ID is specifically designed to identify the link layer address used for ProSe direct communication by a ProSe UE-to-network relay UE, enabling efficient and reliable communication between UEs in proximity-based services.