Question: In a Mobility Management Entity (MME) - Visitor Location Register (VLR) interface, what triggers the VLR to initiate an MM Information Procedure by sending an SGsAP-MM-INFORMATION-REQUEST message to the MME for a target User Equipment (UE)?
Option 1: The state of the SGs association in the VLR is SGs-ASSOCIATED for the target UE.
Option 2: The MME explicitly requests MM information for a specific UE via an initial message.
Option 3: A handover procedure is initiated for the target UE, requiring updated MM information.
Option 4: Periodic location updates are due for all UEs registered with the VLR.
Explanation: An SGsAP-MM-INFORMATION-REQUEST message is typically sent when there's an established association that warrants information exchange. The state of the SGs association being SGs-ASSOCIATED for the target UE indicates a pre-existing connection context, making it plausible for the VLR to initiate such a procedure without needing external triggers like explicit MME requests or handovers.