Question: Which of the following best describes the primary purpose of the 'MBMS RAB Establishment Indication' message in a UTRAN network?
Option 1: To request the establishment of an MBMS Iu signalling connection from the Core Network (CN) to the Radio Network Controller (RNC).
Option 2: To inform the Core Network (CN) about the successful establishment of an MBMS RAB, utilizing a connection-oriented signalling bearer mode.
Option 3: To release an existing MBMS RAB due to inactivity or resource optimization, as initiated by the RNC.
Option 4: To query the CN for the status of all active MBMS RABs within the network.
Explanation: The 'MBMS RAB Establishment Indication' message is sent by the Radio Network Controller (RNC) to the Core Network (CN) to notify it of the successful setup of an MBMS Radio Access Bearer (RAB), enabling efficient management of established MBMS RABs via a reliable connection-oriented signalling approach.