Question: In the context of E-UTRAN, what is the primary purpose of the 'Target RNC to Source RNC Transparent Container' in inter-3GPP RAT handovers from SAE/LTE to UTRAN?
Option 1: To manage user data transmission between the source and target Radio Access Technologies (RATs)
Option 2: To facilitate authentication procedures across different RATs
Option 3: To transparently pass radio-related information between the handover target and source through the Evolved Packet Core (EPC)
Option 4: To handle billing and charging for inter-RAT handovers
Explanation: The correct answer highlights the container's role in seamlessly transferring radio-related information between the handover target (UTRAN) and source (SAE/LTE) via the EPC, ensuring a smooth handover process without losing critical radio context for maintaining service continuity and quality.