Question: In a Location Services (LCS) scenario, if the Serving GPRS Support Node (SGSN) successfully executes privacy checks but fails to obtain a location estimate for a target User Equipment (UE), what may the SGSN return to the Gateway Mobile Location Centre (GMLC) under certain conditions?
Option 1: The last known location of the target UE, if available and requested by the LCS client.
Option 2: An error response with a cause code indicating 'Location Not Available'.
Option 3: A request for additional privacy verification to proceed with the location request.
Option 4: A notification to the UE to initiate manual location reporting.
Explanation: According to LCS procedures, if the SGSN successfully executes privacy checks but cannot provide a current location estimate, it may return the last known location of the target UE to the GMLC. This is contingent upon the LCS client requesting either the current or last known location and this information being available.