Question: In the context of Performance Management (PM) for Core Network (CN) Packet Switched (PS) domain, what triggers the counting of a successful GPRS detach procedure initiated by SGSN for the measurement `MM.SuccGprsDetachSgsn`?
Option 1: Sending of "DETACH REQUEST" message from SGSN to MS
Option 2: Receipt of "DETACH ACCEPT" message from the MS at the SGSN
Option 3: Completion of GPRS attach procedure before initiating detach
Option 4: Successful handover of the UE to another SGSN area
Explanation: The correct answer is based on the specific event that marks the successful completion of an SGSN-initiated GPRS detach procedure. Receipt of a "DETACH ACCEPT" message from the Mobile Station (MS) at the Serving GPRS Support Node (SGSN) is the trigger for counting this event as successful, highlighting the importance of signaling completion in managing network performance.