Question: What triggers a UE to initiate PLMN and non-3GPP access node selection for emergency services?
Option 1: Detection of a user request for emergency session and determination that untrusted non-3GPP access shall be used for the emergency access.
Option 2: Loss of 3GPP network coverage and availability of non-3GPP access networks.
Option 3: Receipt of an emergency alert from the network.
Option 4: UE's location in a restricted area.
Explanation: The correct answer is Option 1 because, according to the text, the UE initiates PLMN and non-3GPP access node selection for emergency services when it detects a user request for emergency session and determines that untrusted non-3GPP access shall be used for the emergency access. This highlights the importance of the UE's ability to detect emergency situations and adapt its behavior accordingly to ensure timely and reliable emergency communications.