Question: Which reference point is utilized by GM-PC5 for interactions related to group management functions between group management clients in different VAL UEs, and what is its origin?
Option 1: PMIP (Proxy Mobile IPv6) reference point, originating from mobility management protocols.
Option 2: SGi (Service Gateway Interface) reference point, derived from EPS (Evolved Packet System) architecture.
Option 3: PC5 (Proximity Services) reference point, as described in the context of Proximity-based services (ProSe).
Option 4: S1-U (User Plane Interface) reference point, related to LTE RAN architecture.
Explanation: The correct answer is Option 3 because GM-PC5 utilizes the PC5 reference point for group management interactions. PC5 is specifically mentioned as originating from Proximity-based services (ProSe), indicating its relevance to proximity and group communication services, aligning with the purpose of GM-PC5 in managing group communications between UEs. This highlights the importance of PC5 in facilitating direct device-to-device communications and related service enablers for verticals.