Question: What triggers the source NG-RAN node to initiate handover cancellation and send a Handover Cancel request to the source AMF?
Option 1: Successful completion of the handover procedure
Option 2: Timer expiration, internal failure within the source NG-RAN node, or UE returned to source cell
Option 3: Receipt of a Handover Command from the target NG-RAN node
Option 4: Release of resources reserved for the handover in the target system
Explanation: The source NG-RAN node may attempt cancellation of handover during the handover procedure due to specific reasons such as timer expiration, internal failure within the source NG-RAN node, or UE returned to source cell. This triggers the initiation of handover cancellation and sending a Handover Cancel request to the source AMF to release resources reserved for the handover in the target system.