Question: In a UTRAN network, when an MBMS Session starts, what triggers the movement of interested UEs from PMM-IDLE to PMM-CONNECTED mode for radio efficiency?
Option 1: An explicit MBMS notification sent in the MBMS Service Area, requesting a proportion of UEs to move to PMM-CONNECTED mode
Option 2: Receipt of MBMS Session attributes (e.g., Session Identifier) by the UE
Option 3: Automatic handover from point-to-multipoint to point-to-point links due to network congestion
Option 4: Periodic location updates by UEs in the MBMS Service Area
Explanation: The movement of interested UEs from PMM-IDLE to PMM-CONNECTED mode for radio efficiency reasons is triggered by an explicit MBMS notification sent in the MBMS Service Area. This allows the UTRAN to decide between point-to-point or point-to-multipoint links based on Radio Resource Management criteria, optimizing network resources.