Question: Under what condition(s) will a User Equipment (UE) in RRC_CONNECTED state start timer T310 for a Secondary Cell (SpCell) with an active DAPS bearer?
Option 1: Upon receiving a single 'out-of-sync' indication from lower layers for the SpCell, regardless of running timers.
Option 2: Upon receiving N310 consecutive 'out-of-sync' indications for the source SpCell from lower layers while timer T304 is running, or if no specific timers (T300, T301, T304, T311, T316, T319) are running.
Option 3: When all timers (T300, T301, T304, T311, T316, T319) expire simultaneously for the SpCell.
Option 4: After a manual reset of the UE's radio interface, affecting the SpCell's synchronization status.
Explanation: This option correctly identifies the conditions under which the UE starts timer T310 for an SpCell with an active DAPS bearer. These are: (1) receiving N310 consecutive 'out-of-sync' indications while T304 is running, or (2) upon such indications when none of the specified timers (T300, T301, T304, T311, T316, T319) are running. This reflects the nuanced handling of synchronization issues in RRC_CONNECTED state, balancing between proactive response to persistent problems and avoiding unnecessary actions during transient states or when other relevant processes are active.