Question: Upon receiving an SGsAP-LOCATION-UPDATE-ACCEPT message from the VLR, what action does the MME take regarding the MM context variable 'VLR-Reliable' and what is the implication for the UE?
Option 1: Sets 'VLR-Reliable' to 'true' and waits for the outcome of non-EPS services before sending a response to the UE.
Option 2: Sets 'VLR-Reliable' to 'false' and immediately sends a location update acceptance response to the UE.
Option 3: Leaves 'VLR-Reliable' unchanged but updates it after receiving the outcome of non-EPS services, then sends the location update response to the UE.
Option 4: Sets 'VLR-Reliable' to 'true' and never waits for the outcome of non-EPS services.
Explanation: The MME sets the MM context variable 'VLR-Reliable' to 'true' upon receiving an SGsAP-LOCATION-UPDATE-ACCEPT message, indicating a reliable association. It then waits for the outcome of the location update for non-EPS services before sending a response to the UE, ensuring all aspects of the update are confirmed before notifying the UE.