Question: Which entities are interconnected by the Gz reference point for the transport of service data flow based offline charging information?
Option 1: P-GW (PDN Gateway) and eNodeB
Option 2: PCEF (Policy and Charging Enforcement Function) and OFCS (Online Charging Function)
Option 3: MME (Mobility Management Entity) and SGSN (Serving GPRS Support Node)
Option 4: UE (User Equipment) and APN (Access Point Name)
Explanation: The correct answer is Option 2 because the Gz reference point specifically facilitates communication between the PCEF, which enforces policy and charging rules, and the OFCS, which handles online charging functions. This connection enables the efficient transport of service data flow information for offline charging purposes, aligning with the roles of these components in telecom networks.