Question: In an MBMS (Multimedia Broadcast/Multicast Service) scenario, where a User Service Initiation randomization is defined for a service, how does an MBMS UE (User Equipment) determine the start time for the randomization period if the `initiationStartTime` parameter is not signaled by the BM-SC (Broadcast Multicast Service Center)?
Option 1: The MBMS UE uses a default start time set by the device manufacturer.
Option 2: The MBMS UE uses the time of the last successful service initiation as the reference.
Option 3: The MBMS UE synchronizes with the network to receive a separate timing signal.
Option 4: The MBMS UE uses the time of the Service Announcement reception as the start time.
Explanation: According to the specifications for MBMS User Service Initiation procedures, if the `initiationStartTime` parameter is not present in the user service description signaled by the BM-SC, the MBMS UE defaults to using the time of the Service Announcement reception as the start time for the randomization period. This ensures a standardized fallback approach across all devices, preventing potential conflicts or misunderstandings in service initiation timing.