Question: Under what condition can a Node B initiate the Bearer Re-arrangement procedure in a UTRAN Iub interface context?
Option 1: Immediately after power-up, before any Radio Links are established.
Option 2: At any time after establishing at least one Radio Link for the Node B Communication Context.
Option 3: Only during handover procedures to ensure seamless bearer continuity.
Option 4: When explicitly instructed by the Radio Network Controller (RNC) via a dedicated command.
Explanation: This is correct because, according to the specified procedure, the Node B has the flexibility to initiate Bearer Re-arrangement at any point following the establishment of a Radio Link. This allows for dynamic adjustments as needed after initial setup, ensuring optimal communication context configuration without being limited to specific events like handovers or explicit RNC commands.