Question: What is the primary purpose of transferring a 'Correlation Number' from a PDG, WAG, or AAA server to a DF2 (Delivery Function 2) in the context of Lawful Interception over the X2-interface?
Option 1: To ensure Quality of Service (QoS) for intercepted packet data.
Option 2: To correlate multiple interception events related to a single target identity across different network entities.
Option 3: To authenticate the target's identity (IMSI, NAI, or MSISDN) for lawful interception purposes.
Option 4: To specify the target location for geographic-based interception filtering.
Explanation: The Correlation Number is crucial for linking various interception events that pertain to the same target identity. This enables a comprehensive view of the target's communication activities, which is essential for effective lawful interception. By correlating these events, DF2 can better perform its functionality in managing and processing intercepted data from potentially multiple sources or network entities.