Question: Under what condition(s) must the Relocation Cancel procedure be initiated on **all** existing Iu signalling connections for a User Equipment (UE), where the Relocation Preparation procedure hasn't terminated unsuccessfully?
Option 1: When initiating relocation due to reasons other than receiving a RELOCATION PREPARATION FAILURE message, and there are multiple Iu signalling connections.
Option 2: Upon receipt of a RELOCATION PREPARATION FAILURE message on any one of the Iu signalling connections for the UE.
Option 3: If the Relocation Preparation procedure has successfully terminated on at least one Iu signalling connection for the UE.
Option 4: When the UE has only a single existing Iu signalling connection, regardless of the reason for relocation.
Explanation: This is correct because if the Relocation Cancel procedure is initiated due to reasons other than receiving a RELOCATION PREPARATION FAILURE message, it must be applied to all Iu signalling connections where the Relocation Preparation hasn't ended in failure, ensuring consistency across all connections for the UE under those specific circumstances.