Question: What action does a UE (User Equipment) take when cell re-selection occurs while timer T390 is running, in accordance with RRC protocol?
Option 1: Perform actions upon going to RRC_IDLE with release cause 'RRC Resume failure'
Option 2: Stop T390 for all access categories and perform specified actions as per RRC protocol
Option 3: Indicate to the lower layer to stop inactivePosSRS-TimeAlignmentTimer and release srs-PosRRC-Inactive
Option 4: Update Timing Advance and stored RSRP without stopping T390
Explanation: According to the RRC protocol, when cell selection or re-selection occurs while timer T390 is running, the UE stops T390 for all access categories. Following this, the UE performs specified actions to ensure seamless network operation and resource management during cell transitions with active timers.