Question: What triggers the measurement of 'Attempted identification information requests from a partner (new) SGSN for subscribers de-registering' in a telecom network?
Option 1: Sending of the 'Identification Response' message to a partner (new) SGSN
Option 2: Receipt of the 'Location Update' message from a UE (User Equipment)
Option 3: Receipt of the 'Identification Request' message from a partner (new) SGSN
Option 4: De-registration of a subscriber from the current SGSN without a request
Explanation: The correct trigger for measuring attempted identification information requests is the receipt of an 'Identification Request' message. This counts incoming requests from a partner (new) SGSN for subscribers de-registering, reflecting network interaction with other SGSNs during subscriber mobility events, crucial for seamless handovers and subscriber management across different networks.